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MECHANICAL DRAWING. 



WRITTEN FOR THE USE OF THE NAVAL CADETS 
AT THE UNITED STATES NAVAL ACADEMY. 



F. W. BARTLETT, 

Lieutenant Commander U. S. Navy. 



FIRST EDITION'. 
• \ FIRST >TP[Otr^^A^D.>:' 



NEW YORK: 

JOHN WILEY & SONS. 

London: CHAPMAN & HALL, Limited. 

1901. 



THE LIBRARY OF 
CONGRESS, 

Two Copies Received 

AUG. 12 190! 

COPVRIQHT ENTRY 

LASS^XXa N» 
COPY B. 



f-t, 



vb 







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Copyright, igoi, j 

BY 

F. W. BARTLETT. 



ROBERT DRUMMOND, PRINTER. NEW YORK. 



PREFACE. 



The attempt is made in this treatise to find the methods 
of practical work in use in most drafting-rooms and to give 
these methods in detail for the use of those studying Mechan- 
ical Drawing. 

The author has endeavored to eliminate any personal 
peculiarity of method, and has based the treatise on the 
methods in use in the United States Navy, as far as these 
methods could be determined. As general methods differ 
slightly, the drawings referred to for the general instruction 
have been those of the Bureau of Steam Engineering of the 
Navy Department, and the methods of that bureau have 
been followed. The special methods of the Bureau of Ord- 
nance and of the Bureau of Construction are studied and 
used after the main course is completed. The differences 
are, however, slight and refer principally to center lines 
and dimension lines. The Bureau of Ordnance uses the 
decimal scale also. 

All the minor points of method that are found only by 
experience cannot be given to a large class by a small corps 
of instructors, and the endeavor is made to place these 
methods where they may be found and studied. The in- 
structor may then refer each one to the book instead of 
giving to each individual the same detail. 

iii 



IV PREFACE. 

The system of instruction urged does away with copying. 
In fact, no copying is allowed and no drawings are available 
for copying. 

The First Drawings are purposely full of detail, so that 
the eye, mind, and hand may be trained to accuracy together, 
each depending on the others. The instruction lessens as 
the figures follow each other, only the new and most impor- 
tant points being noticed. The attempt is made to have 
the triangular scale used so that it will be thoroughly 
understood. 

No Geometry or Descriptive Geometry is given, as 
these branches are taught in another department at the 
Naval Academy. 

All but Sheet III has been carefully criticised by Mr. 
A. M. P. Maschmeyer, Chief Draftsman in the Bureau of 
Steam Engineering at the Navy Department, and the author 
is much indebted to him for his kindness and his thorough 
criticism. 

The naval officers associated in this work have assisted 
materially with suggestions. I am particularly indebted to 
Lieut. Commander John L. Gow, U. S. Navy, for his un- 
sparing and accurate criticisms. 

F. W. Bartlett, 

Lieut. Commander, U. S. N. 



CONTENTS. 



PACK 

The Drawing Course , ix 

Use of Instruments i 

Drawing-board , i 

Thumb-tacks 2 

Pencils and Pencilling 2 

Sharpening the Lead — 3 

Ink 5 

Red Ink 6 

T Square 6 

Triangles 8 

To Test Triangles g 

The Triangular Scale 10 

To Use the Scale 13 

Triangular-scale Guard 13 

Right-line Pen 13 

Use of the R. L. Pen 14 

To Examine and Test the R. L. Pen 18 

To Sharpen the R. L. Pen 18 

Compasses ig 

To Test the Compasses 20 

To Use the Compasses 20 

Extension-bar 21 

Bow Spacers 22 

Bow Pencil and Bow Pen 23 

Dividers 24 

To Use the Dividers 24 

Irregular Curves 25 

Protractors 26 

To Use the Protractors 26 

Erasers 27 

Erasing Shields 28 

Horn Center. ......... . 28 

Brushes 29 



VI CONTENTS. 

PAGE 

Pricker 29 

Beam-compasses or Trams 29 

Foot Rule 30 

Calipers 30 

Splines 31 

Lead-wire 31 

Paper-cutters 31 

General Directions 32 

Stretching Paper 32 

Profile Drawings 34 

General Arrangement 34 

Working Drawings 35 

Views 36 

Projections 38 

Lines... 40 

Center Lines 41 

Shade Lines 43 

Shafts and Other Cylindrical Objects 49 

Sections 50 

Hatching 51 

Breaks 56 

Dimension Lines; Dimension Extension Lines 57 

Threads 62 

Square Threads 67 

Bolts and Nuts. 70 

Jam-nuts 74 

Tails 74 

Working, Border, and Cutting Lines 75 

Legend, Lettering, Scale, etc 76 

Block Letters 79 

Free-hand Lettering 83 

Scales 83 

Line Shading and Tinting 85 

Flat Surfaces 85 

Cylinder 86 

Interior of Hollow Cylinder 89 

Cone 89 

Sphere gi 

Tinting 92 

To Prepare the Tint 92 

To Lay on a Flat Tint 93 

Stippling 95 

Tinting. Cylinder 96 

Cone 97-98 

Sphere 98 



CONTENTS. Vii 

PAGE 

Tracing g5 

Blue-printing g8 

Sketches gg 

Plan of Procedure in Making a Drawing 102 

Pencilling the Drawings 103 

Plan of Procedure in Inking 104 

General Remarks 105 

First Drawings 106 

General View of Sheets I and II 106 

Sheet I. Straight-line Drawing 107 

Fig. I. Horizontal Full Lines log 

2. Vertical Broken Lines no 

3. Horizontal Heavy Lines m 

4. Vertical Heavy Lines 113 

5. 45° Triangle 114 

6. 45° Triangle 115 

7. 60° Triangle 116 

8. 60° Triangle 117 

9. 45° Triangle ng 

10. 45° and 60° Triangles 120 

11. 45° and 60° Triangles; no T Square 121 

12. 60° Triangle 122 

13. Bow Spacers 124 

14. Dividing Lines into Parts 125 

15. Dimension Lines and Figures 126 

16. Section: Hatching 128 

17. Line Shading 129 

18. Protractor 130 

Legend 132 

Sheet II. Curved-line Drawing 133 

Fig. I. Compass 133 

2. Compasses, Bow Pencil and Pen 135 

3. Bow Pencil and Pen 136 

4. Bow Pencil, Bow Pen, Bow Spacers. . 137 

5. Fillets 138 

6. Arcs and Straight Lines 140 

7. Two Arcs and Straight Line Joining Them 143 

8. Protractors, Arcs, and Straight Lines 145 

9. Tangent Arcs 146 

10. Connecting Arcs 147 

11. Connecting Arcs 148 

12. Extension-bar ■. 150 

13. Ellipses; Irregular Curves 151 

14. Irregular Curves 153 

15. Shading Fillets 154 



Vlll CONTENTS. 

PAGE 

Fig. i6. Shade Lines 155 

17. Heavy Lines with Narrow Space Between 156 

i8. Shading Circles; Hatching 157 

Legend 158 

Sheet in. Projections, etc. Working Drawing 159 

Description of Models. General Directions 159 

General Description of Sketching 160 

General Directions for Drawing Sheet HI 163 

Legend 163 

Positions of Views on Sheet 164 

Model 1 165 

Sketching 165 

Dimensions 167 

Sections 168 

Directions for Drawing 170 

Model II 171 

Sketching 171 

Dimensions 174 

Section 174 

Directions for Drawing 175 

Model III 176 

Sketching 176 

Dimensions 178 

Section 179 

Directions for Drawing 179 

Legend, Sheet III 181 

Standard Dimensions of Bolts and Nuts for the United States 

Navy 182 

Standard Hatching 183 

Special Methods of the Bureau of Ordnance, U. S. Navy 184 

Special Methods of the Bureau of Construction, U. S. Navy... 185 

Index 187 



THE DRAWING COURSE. 



It is considered that the most important parts of the 
course are : 

First. Instruction in the use of the instruments; in mak- 
ing clean, sharp lines; in connecting lines cleanly together; 
the technique generally. 

Second. Instruction in quickly and accurately making a 
correct, dimensioned sketch of any piece of mechanism ; and 
from the sketch making a working drawing so that the 
mechanism may be reproduced with certainty. 

Third. Instruction in carefully and accurately making 
tracings and blue-prints from either the inked or pencilled 
working drawings. 

Fourth. Instruction in quickly and accurately reading 
drawings. 

Fifth. Special instruction in engineering, ordnance, and 
ship-building methods. 



MECHANICAL DRAWING. 



USE OF INSTRUMENTS. 

Note. — As center lines cannot well be printed in red ink, all center 
lines are drawn as fine broken lines with long dashes and short distances 
between the dashes. 

Drawing-board. — One edge only of the drawing-board is 
made a true plane. The accuracy of the drawings depends on 
this plane being true. This is the "working-edge" and is 
marked by a circular stamp along the middle of the upper face 
of the board. When in use, this "working-edge" is at the 
left, the stamped face upwards. 

The "working-edge " of the board is considered for con- 
venience as the W. side of the board, so that the side away 
from the position of the draftsman is the N. side of the board, 
etc. 

The lines from E. to W. on the board are considered hori- 
zontal lines ; those from N. to S. vertical lines. 

When beginning a new drawing, take the drawing-board 
and T square to the pattern-maker to have them " trued up " ; 
in other words, to make the "working-edge" of the board 
and the sliding-edge of the T square true planes. At the 
same time the T square is tested to make sure that the top 
edge of the blade is at right angles to the sliding-face of the 
head. 



2 MECHANICAL DRA WING. 

The drawing-board is to be kept horizontal or very shghtly 
inchned at the height desired, the work done standing. 

When first beginning work, swing the board around until 
the best light is obtained, the direction of the light to be from 
the left-hand top (N. W.) corner. Test this by placing the 
T square and triangle in position and noting if the edges to be 
drawn by are in light or shadow. While drawing, test often 
for light, as the work will be poor if the light is bad and the 
eyes will suffer. 

Thumb-tacks. — These are used in securing drawing- and 
tracing-paper on the boards. When first inserted in the paper 
the heads may be tipped at an angle towards the center of the 
paper, so that when straightened up in pushing them into the 
wood they may slightly assist in stretching the paper. 

They are always pushed down firmly when used. 

To secure paper or tracing-cloth on the boards. — Place the 
paper in position as desired ; put in a thumb-tack at the 
middle of the top line of the paper; slide the hand with 
a gentle, firm pressure from this tack down to the middle of 
the bottom line of the paper and, while firmly holding the 
paper as stretched, insert another thumb-tack; begin at the 
center of the board and slide the hand to the right with the 
same pressure and insert a tack at the middle point of the 
right-hand line of the paper; do the same to the left; begin 
again at the middle of the board and slide the hand with the 
same pressure towards a corner and insert a tack; repeat for 
the other corners. In each case, be sure to keep the pressure 
until the tack is fast. It may be necessary to insert tacks 
between those already placed. In each case press the paper 
as described. 

Pencils and Pencilling. — The pencil-work of a drawing is 
most important. Good ink-work never hides defects of bad 
pencil-work. The accuracy of the drawing depends almost 
entirely on good pencil-work. 

Make clean, sharp lines — not faint ones; it is difficult in 



USE OF INSTRUMENTS. 3 

inking or tracing a drawing to find the faint lines, and the eyes 
are strained by the close vision required. Even though slight 
depressions are made in the paper by making firm lines, it is 
best to do this and save the eyes. 

Draw all pencil-lines fi.ill and broken as required. It is a 
waste of time to begin and stop the pencil-lines at the exact 
points where the ink-lines will begin and end. Sweep through 
the terminal points of the line, but no farther than necessary. 
Pencil-lines are easily erased after the inking is completed. 

The leads in the pencils used should be HHHHHH or 
HHHHHHH. These marks are found on the pencil or on 
the box of leads used with the artist's pencil. 

Never use a soft lead for any purpose on a drawing-board. 

Sharpen the pencil-points frequently 

The best point for the pencil is the long chisel-point 
narrowed to about one-third the thickness of the lead. 

Fig. I shows the proper sharpening of the lead-pencil The 
longer bevels are from 2" to 3" long, and the shorter ones from 
i/^'' to 2" long, axially. 

Fig. 2 shows the proper method of sharpening the lead for 
the artist's pencil. The length of the longer bevel along the 
axis of the lead is from 3^" to i^". 

It is even advisable to make the point thinner as in Fig. 3, 
but there is more danger of breaking the lead through care- 
lessness. For the compasses and bow pencil, narrow the flat 
edge still more and take care to place the flat edge of the 
pencil-point so that it is tangent to the arc drawn. 

Another good point is made by sharpening the lead with 
a cut clear across at an angle, as shown in Fig. 4. This 
method is by many considered best, as the outer skin of the lead 
is hardest and wears better. Also, less time is required for 
sharpening, and the point is rounded. It is considered 
especially good for compasses and bow pencils. 

Sharpening- the Lead. — If a file is used, the lead is sharp- 
ened by rubbing it along the rougher side of the file until it is 



MECHANICAL DRA WING. 



shaped and then finishing on the smoother side of the file. 
Support the end of the file when sharpening the lead. 

In the last sharpening, roll the lead a little on the file so 



ll 



I 



(^ 



I 






as to round the corners slightly. Finally, rub the flat edges 
on a piece of drawing-paper, rolling as before; this will remove 
the rough edges left by the file. 



USE OF INSTRUMENTS. 5 

As files soon wear out, many prefer pads made of strips of 
sandpaper. 

It is a good practice to have one end of the pencil sharp- 
ened with a chisel-edge and one with a round (needle) point 
for marking dimensions, both leads hard ; but it is better for 
very accurate work to mark off dimensions with the sharp 
points of the dividers or bow spacers ; or, better still, if such 
an article is at hand, the pricker. 

In using the pencil, keep it nearly vertical and keep the 
arm away from the body. Do not hold the pencil so that the 
point is in the angle between the guiding-edge and the paper: 
keep it vertical. 

Use the pencil with a free sweep, keeping the eye along 
the line of the T square or triangle if possible. 

Always draw from left to right, and always away from the 
bod}'. 

Considerable practice will be required in order to draw a 
line accurately through two points when the pencil is guided 
either with the T square or the triangle. In the case of the 
triangle, for instance, if the two points are marked and it is 
desired to draw a line through the middle of each mark, place 
the triangle very near the points but not exactly up to them, 
as the pencil must be held vertical and not bent over to fit 
sharply into the angle between the triangle and the paper. 
Hold the pencil properly and draw a short line through the 
left-hand point ; if it is not in the center of the mark, the tri- 
angle must be moved a little and the attempt repeated. After 
the line is correct, carry the hand .along in the same position 
to the other point and again test by a short line. When the 
two short lines agree with the centers of the two marks, return 
to the left and sweep the line across, carefully holding the 
hand in the same position and resting the last two fingers on 
the triangle. 

Ink. — The best drawings can be made only by using the 
best Indian or Chinese ink. This consists of carbon mixed with 



6 MECHANICAL DRA WING. 

some adhesive substance, and lies wholly on the surface when 
used on the drawing-board, and can be readily erased if neces- 
sary. It is furnished in blocks of varying sizes, and is ground 
in water in any convenient receptacle. Special forms of ink- 
saucers are made with glass covers to reduce evaporation and 
keep out dust. 

As considerable time is required to mix the ink, and as ink 
must be freshly mixed to be good, it is often necessary to use 
one of the kinds of permanently mixed inks furnished in 
bottles. The results are not as good as can be obtained with 
the stick ink, but the time required for mixing the ink cannot 
always be spared. 

Red Ink. — This is used for center lines, etc. It flows 
more freely than the Indian ink, and greater care must be 
observed in its use, as it is much more likely to run out of the 
pens against the triangles and T squares. The outside of the 
pen must be carefully wiped after the pen is filled ; the pen 
must not be filled as full as with the black ink ; and care must 
be taken not to hold the pen too near the triangles or T square 
when making lines. 

Except where a section is marked, all red-ink lines are fine 
lines. 

T Square. — On the working-edge of the drawing-board 
and on the T square depend primarily the accuracy of the 
drawings. 

The T square consists of the head and the blade. Some- 
times they are fixed at right angles to each other ; and some- 
times the blade is movable and may be clamped at any desired 
angle with the head. The fixed blade answers all practical 
purposes for general work. 

The sliding-edge of the head of the T square is made a 
true plane, and this edge slides along the " working-edge " of 
the drawing-board, so that all lines drawn along the blade in 
the various positions of the head will be parallel. In the 
fixed-blade type, the top of the blade is accurately planed so 



USE OF INSTRUMENTS. 7 

as to be at right angles to the head, so that all lines drawn 
along this top of the T square will be at right angles to the 
"working-edge" of the board. Since the triangles are 
accurately squared, the vertical lines drawn when the triangle 
rests on the T square in position will be parallel to the 
' ' working-edge ' ' of the board. 

Lines should of course be drawn with the upper edge of 
the T square only as a guide. 

The T square is used for all horizontal lines. It cannot 
be depended upon for the vertical lines, as the bottom of the 
board is not planed at right angles to the " working-edge." 

It is held with the head firmly pressed against the " work- 
ing-edge " by the left hand, and is moved along that edge by 
the left hand. It must never be moved with the right hand 
on the blade or with both hands pushing the blade, or with the 
right hand assisting the left by pushing on the blade at the 
same time as the left hand moves the T square. 

Stretch the first finger and the wrist of the left hand along 
the head of the T square equally on both sides of the blade, 
making the support as long as possible. 

The vertical lines are drawn by using the J-riangles as 
guides. These are moved alon'g the T-square as it is firmly 
held in position Avith the left hand. As both hands are 
required in using the triangles in this manner, after the triangle 
is nearly in the proper position, slide the left hand along the 
blade of the T square, always pressing to the right and down- 
ward, and hold the T square with some of the fingers and 
move the triangle along with the others. Often test the posi- 
tion of the T square by moving the left hand back to the head 
of the instrument, again sliding it along the blade as before. 

Never guide a knife in cutting paper with the upper edge 
of the T square. Use the lower edge; or, better still, use the 
knife with no guide but the eye and the line drawn for cutting. 

Use no weights to hold the T square or triangles in posi- 
tion. 



8 MECHANICAL DRAWING. 

Triangles. — The triang-les are 45° and 60°. The 45° tri- 
angle has equal angles at the ends. The 60° triangle has one 
60° and one 30° angle. The other angles of both triangles 
are right angles and are very accurately constructed. In the 
case of the 45° triangle, the two shortest sides are equal in 
length ; in the 60° triangle, the shortest side is twice the length 
of the longest. 

The triangles rest against the T square and are used in 
drawing the vertical lines of the drawings. These lines are 
then parallel to the "working-edge" of the drawing-board. 
In drawing these vertical lines always place the triangle on the 
T square so that the left side of the triangle will be the one ver- 
tical. In this manner the light will always come from the left. 

To Draiv Parallel Lilies with the Triangles. — After one line 
is drawn with a triangle, to draw others parallel to it, place 
the triangle near the line and parallel to it, as if the line 
were to be drawn again. Do not attempt to place the triangle 
edge exactly on the line, as it will be found very difficult to 
get it exactly right, whereas it may be readily brought near 
and parallel. Hold this triangle firmly and bring the other 
triangle against one edge of it; then hold the second one 
firmly and move the first one along the edge of the fixed 
one until the desired point is reached, when the line may be 
drawn. This may be repeated for a number of lines parallel 
to the first one drawn. The left hand must hold both triangles 
when the lines are drawn, some of the fingers on each; 
generally the thumb and last two fingers hold the fixed tri- 
angle, and the first and middle fingers move along and secure 
the one moved. 

Angles of 15°, 30°, 45°, 60°, 75°, and 90° may be drawn 
by the combination of the T square and the two triangles. 

Never construct angles by drawing lines along adjacent 
sides leading from a vertex. It is even well to cut about y(" 
from all the corners of the triangles, as these corners are often 
bent and unreliable. 



USE OF INSTRUMENTS. 



In drawing lines Avith the triangles as guides, always 
arrange so that the hand holding the R. L. pen rests on the 
triangle. 

To Test TriciJiglcs. — For the straightness of the edges, 
an accurate steel straight-edge is generally a sufficient test; 
but if great care is required, the following method may be 
used: Push a very fine needle vertically into the paper; at a 
distance just less than the length of the edge to be tested, push 
another needle of the same kind into the paper vertically. 
Place the edge to be tested against the needles and draw a, fine 
line, holding the pencil with great care and always in the same 
position relatively to the edge. Place the edge on the other 
side of the needles and drawn another line. The errors are 
doubled. ^ 

To Test the Right Angle. — Place the triangle on the T 
square and draw a vertical line through a point chosen. Re- 
verse the position and draw another line through the same 
point. The error is doubled. 

To Test the ^5° Angle. — Fig. 5. Draw accurately a large 
circle. Lay the 45° triangle in position on the T square and 





Fig. 5. 



Fig. 6. 



draw lines through the center as shown. Test with the T 
square the horizontal accuracy of the intersections a and b, c 
and d. An additional test may be made by spacing off ah with 
the dividers and comparing the length with bd, dc, and ca. 

To Test the 60° Angle. — Fig. 6. Draw accurately a large 



lO MECHANICAL DRAWING. 

circle. Draw the horizontal center Hne. With the 60° triangle 
in position on the T square, draw the 60° lines as shown. Test 
with the T square the horizontal accuracy of the intersections b 
and c,/ and e. Space be and compare with cd, de\ ef, fa and ab. 

To Test the jo° Angle. — Use the above method, drawing 
also the vertical center line. 

The Triangular Scale. — The triangular scale is used for 
all measurements on the drawing-board, and is an instrument 
of great accuracy and should be carefully treated. 

This scale should never be used except on the drawing- 
board. 

It should never be used for measuring any piece of 
mechanism, as it would soon have its edges battered and would 
be useless for accurate work. Lmes should never be drawn 
along its edge ; in other words, it should never be used as a 
ruler. 

Distances should never be taken from it by compasses or 
dividers, as the points of these would ruin the scales ; besides, 
this method of measuring is not as accurate as that of using the 
scale properly. 

There are ten different scales on the rule furnished, so that 
drawings may be made from ' ' full size ' ' to -Jg- size by using^ 
the different scales. 

Small figures on the right or left indicate the scales. 

The principal scale is marked 16 and is the only one on 
that flat of the rule. This is the " full size " scale where the 
foot is divided into inches and the inches into halves, quarters, 
eighths, and sixteenths; hence the 16 scale. 

As most small measurements in engineering practice are 
given in these fractions of an inch, this scale is the common 
one — being like the ordinary one-foot or two-foot rule. 

Another scale, marked 10, is also the only one on its flat 
of the rule, the foot being subdivided into inches and the inches 
into tenths. This scale is used in ordnance work in the U. S. 
Navy. 



USE OF INSTRUMENTS. II 

The other scales are for the purpose of making drawings of 
reduced sizes. The figures to the right or left indicate what 
number of inches or what portion of an inch represent one foot. 
Thus, to make a drawing of "one-fourth size" or "one- 
quarter size," instead of using the i6 scale and mentally cal- 
culating each dimension in order to draw it one-fourth its 
actual size, use the scale marked 3. This means that 
3" = I foot, or that a distance of 3" is used to represent a foot 
of length and is divided up into twelve parts, each representing 
one inch. These representative inches are again divided into 
halves, quarters, and eighths. Then, instead of calculating a 
distance, it is taken directly from this scale, the calculation 
already made, so that the distance marked off will be exactly 
one-fourth of the true distance. 

The other scales are for the same purpose for different frac- 
tions of full size. 

Mark. Size. Stated on Drawings. 

16 Full size Scale, full size 

10 Full size Scale, full size, decimal 

4 One-third Scale, 4" = i foot 

3 One-fourth Scale, 3" =1 foot 

2 One-sixth Scale, 2" = i foot 

i^ One-eighth Scale, i^" = i foot 

I One-twelfth Scale, i" = i foot 

f One-sixteenth Scale, f ' = i foot 

^ One-twenty-fourth Scale, ^" = i foot 

f One-thirty-second Scale, f" = i foot. 

Of course, as the fraction of full size is reduced, the number 
of divisions on the representative foot is lessened ; for instance, 
on the scale of ^'' = i foot the smallest division of the three- 
eighths inch represents one inch of the full size, and the inches 
are not marked with figures. 

For all except the 16 and 10 scales there are two scales 
on the same flat, so that either may be used. As one of these 



1 2 ME CHA NIC A L D RA WING. 

scales is always equal to twice the other, there is no difficulty 
in taking off any dimension. 

For distances over one foot the scales are marked for feet, 
beginning from the o mark. For instance, using the scale of 
ji^'' = I foot, the o mark is towards the center of the rule, 
and, looking towards the right, we find along the same line on 
which the o is placed a figure 2. This is 2 feet. Farther on 
is a figure 4 for 4 feet. The unmarked lines between O and 

2 and 2 and 4 are i foot and 3 feet respectively. 

Note that the inches and feet are always on the same line 
as the o mark. 

If using the scale at the other end of the same flat, the 
3" =r I foot scale, we find that the o mark is below the flat 
surface and on the curved portion. Then, for using this scale 
for distances of over one foot, we must look along the line 
where the o is placed or in the curved portion. Here we find 
I and 2 only. In order then to measure 2 ft. 7^'', we place 
the 2 mark at the starting-point and follow along to o and 
then find 7" and then the y%" . 

To measure 3 ft. jyk" on the scale of i^'' = i foot, we 
look along the flat portion in line with the o for that scale and 
find that the mark for three feet must be between 2 and 4. 
This is placed at the starting-point and the 3 ft. and yy%" found 
as before, only to the left. 

It may be advisable to place the 77^/8'' mark at the starting- 
point of the measurement and measure on to O and then to 

3 feet. 

For a "half-size " drawing, the 16 scale is used, the divi- 
sion by 2 made mentally. 

For a "double-size drawing," "triple-size drawing," 
etc., use the 16 scale and perform the multiplication mentally. 

For a drawing smaller than -jL- size, use the smallest scale, 
the y%" =■ \ foot, and mentally divide as for " half-size " above. 

In a drafting-room flat scales are much used instead of the 
triangular scale. 



USE OF INSTRUMENTS. 13 

To Use tJic Scale. — Lay the scale along the line to be 
measured so that the desired scale is away from the body and 
thus in good light. Adjust the position of the marks as 
described above and mark the ends of the dimension obtained 
either with a "needle-pointed " lead-pencil, a pricker, or the 
point of the bow spacers or large compass. The metallic 
points are best, as they are sharper. Mark the points distinctly; 
send the metallic points through, but do not make large holes 
in the paper. The point .is marked distinctly to save the eyes 
when it is to be found and used later, but the paper must not 
be ruined by carelessness. 

In marking these points, the sharp pencil or metallic point 
should never mar the scale, but the instrument should be slid 
down along the scale — lying flat against it if possible. 

Triangular-scale Guard. — This is of value when the same 
scale is used for any length of time ; it is clamped on the 
triangular scale so that the desired scale may be readily 
found. 

Right-line Pen. — The right-line pen is used for drawing 
all ink-lines that are not arcs of circles. It consists essentially 
of two sharpened steel points or nibs secured firmly together 
or made from one piece of steel. The steel nibs tend to 
separate and are kept in the desired position by means of the 
small screw. 

The ink is introduced between the nibs of the pen by the 
rubber-topped ink-dropper or the quill pen attached to the cork 
of the bottle, if such are provided. If not provided, a steel 
pen is the best thing to use. In filling the R. L. pen in any 
of these ways, hold both the R. L. pen and the other imple- 
ment nearly vertical and bring the points of the two instruments 
together with the point of the other instrument inserted 
between the nibs of the R. L. pen, when the ink will freely 
run into the R. L. pen. 

A thin strip of paper is sometimes used, but it is a bad 
practice, as small portions of paper may be caught in the pen. 



H 



MECHANICAL DRAWING. 



Another method is to dip the R. L. pen in the ink, in 
which case the outside of the pen must be very carefully wiped. 

The ink is held in place by capillarity, and is drawn out as 
the pen is carried along the paper. 

Ordinarily fill the pen only to a height of one-quarter of 
an inch, as the ink will probably dry before being" used; when 
drawing heavy shade lines, fill the pen as full as it will hold 
with ink. 

Never fail to wipe off the outside of the nibs of the pen after 
filling with ink. 

Use of the R. L. Pen. — The pen is held vertical; the 
screw-head away from the guide ; the middle finger against 




Fig. 7. 

the opening of the nibs on one side and the thumb higher up 
and against the opening of the nibs on the other side; the 
upper part of the pen resting in the outer joint of the first 
finger ; the last two fingers resting on the T square or triangle 
as a guide. Note carefully Fig. 7. 



USE OF INSTRUMENTS. IS 

The reason for holding the pen as described is that there 
is no danger of changing the opening of the nibs by greater 
or less pressure put on them by the thumb and fingers. 

If the thumb and fingers press on the top and bottom of 
the nibs, the least change of this pressure will cause a variation 
in the width of the line, as in Fig. 8. 



Fig. 8. 

By holding the pen properly, a line of equal width, as far 
as this liability to error is concerned, is secured. 

The pen is guided by the T square, triangle, or irregular 
curve, and it must be carefully noted that these are for a guide 
only. The pressure against the guide must be light and 
uniform, as a variation of this pressure will produce a variation 
in the width of the line, as in Fig. 9. 



Fig. 9. 

The proper method of holding the pen will assist in pre- 
venting this defect, as the nibs are held more or less firmly in 
position by the fingers. The nibs of the pen must be kept 
parallel to the guide, as, if they are d«ragged along diagonally, 
a ragged line will be made. The pen must not be held too 
close to the guide, as the ink is likely to flow out suddenly and 
make a blot against the guide; if held vertical, the curvature 
of the nib will prevent this accident. 

In drawing ink-lines a positive and constant pressure must 
be maintained directly downwards ; this pressure varies with 
the sharpness of the pen and the smoothness of the paper. 
With a very sharp pen and very smooth paper an extremely 
light pressure is required; but with a dull pen and paper full 
of depressions and heights considerable downward pressure 



1 6 MECHANICAL DRAWING. 

must be maintained. This downward pressure is entirely dis- 
tinct from the pressure against the guide (T-square, triangle, 
etc.). Each one by practice must determine for himself what 
downward pressure is required for the special pen and paper 
used. 

Both nibs must rest on the paper equally and must be 
carried evenly along the guide ; if one nib presses harder than 
the other, a ragged line is produced, as in Fig. lo. 



6 

Fig. io. 

a shows where the upper nib has cut a clean, firm edge, 
and b where the lower one has been the only one cutting a 
sharp edge. 

The body must be moved about as necessary when using 
the R. L. pen. The important thing is to make a good line. 
So the hand and arm must be first arranged and the body 
moved so as to leave freedom of movement to the arm. When 
holding the pen as described the body will have to be moved 
well to the left, so that instead of the eye being directly over 
the line drawn it will be looking along the line from above and 
to the left. 

Always keep the arm free from the body. 

Draw away from and not towards the body. 

When drawing ink-lines with the use of irregular curves the 
pen must be constantly twisted in the fingers to keep the nibs 
parallel to the edge of the curve. Considerable practice is 
required before good work of this kind can be done. 

The R. L. pen may also be used without a guide for 
drawing curves when it is not desired to take the time neces- 
sary to find the exact curved lines on the irregular curve. 
Rest the last two fingers on the board ; carefully follow the 
curve drawn in pencil ; twist the pen in the fingers to keep the 



USE OF INSTRUMENTS. 1/ 

nibs parallel to the line at each point. This is especially 
valuable in making irregular breaks in metal, instead of using 
the writing-pen, which never makes clean work. 

Always draw lines from left to right. If it should be 
necessary to go over a line a second time, go over it in the 
same direction as before. Never go backwards on a line. 

In case the ink does not flow readily from the pen, a quick 
method, though an inadvisable one, is to run the point across 
one of the fingers of the left hand. A better way is to keep a 
small piece of moistened blotting-paper at hand and touch the 
point of the pen to that ; if the ink fails to run then, clean the 
pen and refill it. On a dry day the pen must be frequently 
cleaned on account of the rapid evaporation of the dissolving 
liquid. 

Sometimes the ink may be made to flow by pressing the 
pen with a blade flat on the paper, using enough pressure to 
cause the blades to slide on each other. This breaks the small 
clot of ink at the point. 

Always test the R. L. pen by drawing lines against a 
guide, as it is never possible to tell surely what kind of a line 
will be made by testing the pen unguided. 

Frequent cleaning of the pen is one of the secrets of making 
clear lines. 

Especial care should be given to cleaning the R. L. pens ; 
they should be cleaned after use, even if only five minutes will 
intervene before using them again ; they should never be put 
away uncleaned. 

A piece of cotton cloth or chamois-skin will thoroughly 
clean the pen; nearly close the nibs and insert the cloth 
between the nibs and draw it through. If the ink is fresh and 
this operation be repeated two or three times, the pen will be 
cleaned. It is well to dip the pen in water before cleaning. 

Do not use too thick a piece of cloth or chamois-skin, as 
the nibs of the pens may snap off. 

To keep all the lines of the same kind of the same width,. 



1 6 ME CHA NIC A L DRA WING. 

do not change the adjustment of the pen in cleaning; draw the 
cleaning cloth between the points carefully without moving the 
screw. 

Do not use a bad pen. If one line is bad, find the cause 
at once. Sharpen the pen; clean it out; or get new ink, as 
necessary. 

To Examine and Test the R. L. Pen. — Note the shape of 
the nibs of the pen when new, and always make them of that 
shape when sharpening the pen. The nibs should be of 
exactly the same shape and length. Look along the edges of 
the nibs, holding the pen-point towards the eye and turning 
the pen in the plane of the nibs, and note if any portions of the 
points are blunt. The bluntness will appear as a line of light 
along the point. 

To Test. — Fill the pen with ink and open the nibs so as to 
make a wide line. Begin to draw the line along a T square 
or triangle and note whether the nibs cut equally. Effects like 
those in Fig. 1 1 will be observed as the nibs are opened and 



Fig. II. 

closed until the proper setting is found. Then if the marks 
of the nibs at the left are equally strong, the nibs are of equal 
length. 

Test for sharpness by drawing fine lines. 

To SJiarpen the R. L. Pen. — Place oil or water as required 
on the stone. Screw the nibs of the pen together until they 
firmly touch. Hold the pen in a plane perpendicular to the 
oil-stone, the opening of the nibs in that plane, and move it 
back and forth along the stone, changing the slope of the pen 
one way and the other as it is moved along the stone, so as to 
grind off the points to the proper curve and also to make them 
of the same length. This makes both points dull, but they 
are of equal length. Next, clean the pen and open the nibs; 
examine the pen as described before and note what parts of the 



USE OF INSTRUMENTS. 1 9 

points need most sharpening. Of course the widest Hght por- 
tions are the dullest. Close the nibs until they just touch, and 
proceed to sharpen as follows: Place one of the nibs on the 
stone, the pen at an angle of about 15°. Move the pen back- 
wards and forwards along the stone, at the same time twisting 
it in the fingers. This brings the edges of the nibs in position 
to be ground down as required. Sharpen principally the por- 
tions noted as dull. Frequently clean the pen and examine 
as before. Continue the operation until no dull places can be 
discovered. Clean thoroughly and test the pen with ink. If 
not properly sharpened, continue as before until exactly right. 
In sharpening, it is likely that one nib may be sharpened too 
much and thus become too short; in that case the ink-line 
drawn will show the defect, and it will be necessary to again 
dull the points and begin over again. Practice soon brings 
efficiency, and nobody can properly sharpen a pen for another, 
as no two people hold the pen in precisely the same way. It 
is very important, then, for each one to persevere and learn 
to sharpen his pen. 

Be very careful about using the stone on the inside of the 
nibs. If a feather-edge be formed in sharpening the pen, open 
the nibs and slip the stone between them. A very few and 
slight movements of the stone will take away the feather-edge. 

There is a limit to the sharpness of pen required, as the 
paper will be cut and ruined if the pen is too sharp. Trial 
only will test for this defect, and it is a very simple matter to 
dull the pen slightly, as explained. 

Compasses. — This instrument is used for drawing arcs of 
circles in pencil or ink, from the largest that can be made with 
the extension bar inserted to a circle of about i^^" in diameter. 
It is an extremely accurate instrument and should be well 
treated. The needle-point is fixed ; either the pencil- or pen- 
point may be put in place and clamped with the screw. These 
points should always be pushed home and carefully clamped; 
and pushed or pulled straight when placing or removing them. 



20 MECHANICAL DRA WING. 

To set the needle-point, put in place the pen-point; close 
the instrument and push the needle-point out until the shoulder 
at the base of the needle just coincides with the point of the 
pen ; then clamp the needle-point. Once the needle-point is 
adjusted, it need never be changed. 

To set the pencil-point, insert the pencil-point in the com- 
passes and push it home and clamp in position ; push the 
pencil out until it coincides with the shoulder of the needle- 
point and clamp the pencil. As the pencil is resharpened, it 
must be pushed out to agree again with the shoulder of the 
needle-point. 

Note. — The pencil-point is sharpened as described under 
the methods of sharpening leads, making the chisel-point 
narrow. 

To Test the Compasses. — Insert the pen-point and close 
the instrument. The needle-point and the middle of the pen 
should coincide. The same should apply to the pencil-point, 
except that allowance must be made for inaccuracy in sharpen- 
ing the lead. Another test for the compasses: Place the pen- 
point in place ; break the knees of both legs of the instrument 
and open the legs until the angle at the upper part is about 
45° and bring the points together; these should closely 
coincide. 

To Use the Compasses. — From the given center the radius 
to be used is measured with the triangular scale and sharply 
and clearly marked. Carefully place the needle-point of the 
compasses exactly in the center of the mark for the given 
center and push it home to the shoulder. This fixes the 
center so that it may be found again when needed, and also 
gives the needle-point a firm support in the wood under the 
paper and preserves the paper. This needle-point must always 
be kept upright by bending the knee above it as much as is 
necessary for whatever circle is drawn. This is very impor- 
tant. Next, open the legs of the compasses and bend the 
knee above the needle-point as required, and also the knee 



USE OF INSTRUMENTS. 21 

above the pencil-point, until both needle- and pencil-points are 
vertical. This may be approximated to with the pencil-point, 
but must be carefully done for the needle-point. When the 
pencil-point is nearly over the point measured, spring the 
instrument open as required until the pencil-point cuts the 
middle of the mark for the measured distance. Test it by 
sweeping a short arc through the point and change as needed 
until the exact center is cut by the pencilled arc. Hold the 
handle of the compasses between the thumb and first finger, 
the instrument nearly vertical ; begin to draw the arc at the 
left and towards the body at a point towards the S. W. ; lean 
the instrument slightly ahead of the position of the pencil-point 
and keep the same amount of forward slope as the arc is swept 
around to the starting-point, always from W. to N., etc., and 
press on the pencil-point firmly and with a constant pressure. 
Never go backwards on the arc. If any part is indistinct, go 
over it again in the same direction. 

Make the line sharp and clean. 

On arriving at the starting-point, the line should coincide 
exactly with that part drawn at the beginning. 

The same methods apply for inking, the amount of pres- 
sure required on the pen-point being determined by experience 
for the kind of paper used. The bending of the knees of the 
compasses in inking is especially important, as both nibs of 
the pen must cut sharply and equally in order to secure a 
clean, sharp line. 

At each change of opening of the compasses, before making 
a line on the drawing, a test should be made on the margin 
of the paper to see that a good line will be drawn. 

The remarks under R. L. pen in regard to cleaning the 
pen apply with equal force to the compass-pen. 

Extension-bar.— When the arc to be drawn is large, the 
extension-bar is put in place above the pencil- or pen-point, 
care being taken that it and the pencil- or pen-point are both 
pushed home and clamped. 



22 MECHANICAL DRAWING. 

In drawing- arcs with the extension-bar in use, it is some- 
times necessary to guide the pencil- or pen-point with one hand- 
while steadying and turning the compasses with the other hand 
on the handle. 

If a "beam compass" is available, it should be used 
instead of the compass with the extension-bar for inking, as 
the latter springs considerably. 

Bow Spacers. — The bow spacers are used for spacing oft 
distances of equal length. The points are also much used for 
marking measured points instead of using a " needle-pointed " 
lead-pencil, as the point of the spacer is much finer than can 
be maintained on any lead-pencil. 

Instead of using the spacers for laying off distances of equal 
lengths, it is more accurate to lay the triangular scale along- 
the line and mark the divisions. Although some of the divi- 
sions thus laid off may be inaccurate, the total length will be 
true and there is less liability of error. When dimensions are 
» not on the triangular scale, the bow spacers are used with 
advantage and are useful in dividing a line into any given 
number of parts quickly, when it is not desired to take the time 
necessary to divide the line geometrically. 

In dividing a line into parts geometrically, the bow spacers 
are useful in laying off quickly and accurately the equal lengths 
on the line laid off at an angle with the given line. 

Constantly keep the index-finger of the right hand on the 
top of the spacers and step off the points along the line to be 
spaced, using the thumb and second finger to swing the instru- 
ment. The steps are made by swinging the points of the 
spacer alternately one way and then the other, pushing each 
point in sufficiently to mark the point well. This necessitates 
a forward and backward movement of the hand for each point 
marked, combined with the swinging movements of the points 
of the spacers. 

If a distance, as 2 inches, is to be spaced off into any 
number of divisions, say ten, estimate with the e3^e about the 



USE OF INSTRUMENTS. 23 

length of one division and set the spacer. Go over the hne 
quickly, making the least amount of puncture possible. The 
amount under or over at the end is again divided by estimate 
and the spacers reset and another trial made very lightly. 
When the exact setting is found, go over the line again and 
puncture the paper sufficiently to clearly mark the divisions. 

Bow Pencil and Bow Pen. — These instruments are very 
useful and are extremely accurate when handled carefully and 
Icept in good order. 

They are used for small arcs. 

The needle-points are adjusted and the instruments tested 
as given under com.passes, noting that the flattened side of 
the needle-point is placed towards the pen- or pencil-point so 
that very small circles may be drawn. 

In using these instruments, the needle-points are always 
pressed in to the shoulder, as stated under Compasses; by 
testing the setting with a small arc and slightly changing the 
screw, very accurate adjustments can be made. 

The remarks under Compasses apply as to leaning the 
instrument a little forward and putting a certain and constant 
amount of pressure on the point ; also in regard to the point of 
beginning to draw the circle. 

In opening and closing these instruments, press the points 
together with the left thumb and forefinger, thus removing the 
pressure from the adjusting-nuts before turning them; this 
preserves the threads of the adjusting-screws and makes the 
operations more rapid. 

Since there are no knees to be bent in the bow instruments, 
the nibs of the pen-points do not evenly touch the paper for 
all radii, and the largest and smallest circles may not be as 
good as the medium-sized ones drawn. When the needle-point 
is set as stated above, it is right for the average of radii used, 
but it may be necessary to change the needle-point for very 
small or very large arcs. 

In Fig. 12, a represents the positions of the nibs of the pen 



24 MECHANICAL DRAWING. 

for the average arcs; b for the very small; and c for the 
largest. The needle must be pushed in for b and out for 

II // w 



Fig. 12. 

c, in order to have the nibs cut equally and produce a per- 
fect line. 

The remarks under R. L. Pen in regard to cleaning the 
pen apply with equal force to the bow pen. 

Dividers. — This instrument has two sharp points, and is 
used on the drawing-board for marking off distances that are 
too great for the bow spacers; and very largely on charts in 
making measurements. 

The clamp at the top, when set, ensures no change in the 
opening of the instrument. Many draftsmen, however, object 
to this clamp and consider that a properly made joint carefully 
handled will never slip. The small adjusting-screw on one of 
the legs enables most accurate work to be done. This is 
called the hair-spring adjustment. 

To Use the Dividers. — Ease the clamp-screw at the head 
of the instrument; open the legs until the points are slightly 
wider apart than the required distance ; set the clamp-screw 
at the head; with the " hair-spring " adjusting-screw close the 
movable point the required amount. 

Distances must never be taken from the triangular scale 
with these instruments, as the points will ruin the scale; and 
this way is not as accurate as the correct method. 

Always lay the triangular scale on the drawing-board and 
measure off the desired distance, marking it by means of one 
of the points of the bow spacers, or, better still, with one of 
the points of the dividers, or a pricker. As the inner sides of 
the divider legs are flattened, these flat portions may be slid 
along down the triangular scale and the points accurately 
marked. 

Take care not to unscrew the "hair-spring" adjusting- 



USE OF INSTRUMENTS. 25 

screw too much, as the screw will become detached from the 
point and the spring may be broken. 

The dividers should always have the adjusting-screw of the 
' ' hair-spring ' ' screwed ' ' home ' ' when put away. 

Irregular Curves. — These are guides for drawing lines that 
are neither straight nor arcs of circles. When a series of 
irregular points are found through which a line is to be drawn, 
begin with some definite point and pick out the portion of any 
one of the irregular curves that seems most likely to fit for the 
greatest length. Test by laying this curved part along the 
line of points, moving the curve about; and, if necessary, 
trying other curves until the longest correct one is found. 
Draw in pencil the curved line until nearly to the end of the 
part that fits accurately. Never draw the line quite to the end 
of the unison of the curves. Before removing the irregular 
curve from its position, make on it faint pencil-marks defining 
the beginning and end of the portion drawn, and also make 
corresponding marks on the paper. Then remove the curve. 
The portion used may then be readily found when inking. 

If the curved figure is a regular one, a reverse curve exactly 
corresponding to the one drawn will be required somewhere in 
the figure. This curve may be marked on the irregular curve 
by carrying the marks placed there across the narrow edge and 
to the under side, where the corresponding marks may be made. 
Then this curve will fit, if the right mark is placed at the point 
exactly opposite the original definite point of starting. 

From the end of the curve drawn, carry on as far as possible 
a new curve, and continue until the entire curve is drawn. 

It. is especially important never to draw the curves quite to 
the point of separation of the required curve and the one on the 
irregular curve, as it will be found difficult to begin a new por- 
tion of curve exactly in agreement with the one ended. This 
is the most difficult part of the use of the irregular curves — to 
have the end of the one and the beginning of the other line in 
unison. 



26 MECHANICAL DRA WING. 

In pencilling and inking with the irregular curves as guides, 
the pencil or pen must be turned in the fingers so as to be 
tangent to the curve drawn at all points. 

Where the irregular curve already contains numerous 
pencil-marks, the new marks may be connected by lines for 
certainty of finding them when inking. 

If the points through which the curve is to be drawn are 
far apart, it is often well to lightly pencil the curve free-hand 
and then draw the portions of it in pencil with the aid of the 
irregular curve; but never fail to draw in pencil first, and mark 
the irregular curve for inking. Do not attempt to draw the 
curve in ink without pencilling it first. 

For small curves it is often a good plan to cut a special 
curve from a thin strip of wood or from a card that is sufficiently 
thick and stiff. 

Protractors. — These are used for laying off angles. They 
are seldom used in machine drawing, but are largely used in 
surveying work of all kinds. 

The protractors should not be used on the drawing-board 
for angles that can be made by the aid of the triangles. 

There are many forms of these instruments, from the heavy 
metal frame with the swinging arms to the plain metal, horn, 
or celluloid article; for ordinary drafting-room work the plain 
metal, horn, or celluloid kind answers all purposes, as the 
number of degrees of irregular angles would be stated on the 
drawing. 

How to Use the Protractors. — Place the 1 8o° marks at 
either side of the arc (not necessarily at the end of the arc) on 
the base line from which the angle is to be measured, and slide 
the protractor along until the notch or mark in the middle of 
the base coincides with the vertex of the angle. Mark at the 
outer circumference the point through which the line defining 
the angle is to be drawn, noting that the inner marks read 
from one end of the arc, and the outer from the other. Re- 
move the protractor and draw the line. 



USE OF INSRTUMENTS. 27 

Erasers. — The rubber ink-eraser should be used very 
carefully on the drawing-board. It erases only a Httle more 
rapidly than the rubber pencil-eraser and is likely to ruin the 
surface of the paper so that it is very difficult to make a good 
ink-line afterwards. With a good quality of paper it may be 
used with comparative safety. The surface must be well 
polished afterwards. 

For erasing on tracing-cloth, the ink-eraser only should 
be used. Afterwards the surface should be rubbed with a soap- 
stone pencil and well polished. 

When an error is made or work in ink is to be removed 
for any reason, use the rubber pencil-eraser and the erasure 
may be made and a good line drawn afterwards. Time 
and light pressure are required, but the line will be removed 
eventually. As the small particles of paper removed become 
electrified, it is necessary to remove them occasionally by 
brushing with the back of the fingers or a cloth ; after the 
ink-line is removed, rub the paper with some smooth, hard 
substance like the handle of the metal ink-eraser or the end of 
a knife-handle or a smooth piece of ivory or agate. After 
that a new line may be drawn with safety. When the new 
ink-line is to be a heavy one, it is well to draw it in parts ; in 
each portion have the pen closed for a comparatively fine line, 
and allow it to dry before drawing the next width of the line. 

The metal eraser should never be used when a new line is 
to be drawn. It is used to remove errors where an ink-line is 
drawn past the required point. It must then be used with 
great care. Use this eraser with the hand above the handle 
and the fingers and thumb well down towards the point. This 
is to prevent the sharp point of the metal from touching the 
paper, as there is no way of telling how deeply this point may 
cut. The flat of the knife-point only must be allowed to do 
the erasing. 

Hold the eraser as described and make a fine, light cut at 
the point where the error begins, and then draw the small 



28 MECHANICAL DRA WING. 

amount of the surface of the paper cut through away from the 
good line. This leaves a clearly defined line as an ending of 
the good work. After that the erasure may be carried on by 
drawing the flat edge of the eraser gently along the paper. 

In case a line may be too broad, it may be made narrower 
by the use of this eraser. Begin at one end of the too heavy 
portion of the line and make a fine cut as described, continuing 
the cut carefully along the line and making the line of the 
desired width. Then each portion may be drawn away gently 
with the eraser as described. 

The black, sponge rubber is used for cleaning the drawing 
after it is completed. This is rubbed across the drawing 
gently after all the pencil-lines have been erased by the rubber 
pencil-eraser. This rubber will simply clean off the dust and 
discolorations made by the hands and instruments. In using 
it, however, do not rub longer than absolutely necessary at 
any part of the drawing, as it will dull the ink effect. Especial 
care should be taken at parts of the drawing where the ink 
Work is heavy, as its effect will be seriously marred. 

The best cleanser for the drawing-paper is stale bread that 
is not too dry. 

Erasing- shields. — These are of thin metal with small 
openings of various shapes that will fit over small portions of 
the drawings to allow of erasing just what is desired and no 
more. 

Horn Centers. — These instruments are used when a great 
many circles are to be drawn from the same center. They 
should never be used except when absolutely necessary. If 
the compasses are fairly bent as described and the bending is 
done for each circle of varying radius, the center in the paper 
will generally last as long as is required. In case the center 
in the paper is enlarged or torn, the horn center must be used, 
but, as a rule, it is a sign of carelessness if a horn center 
appears on the drawing-board. Of course, in special drawings, 
where trams are used, or in line shading, the horn center is 



USE OF INSTRUMENTS. 29 

absolutely necessary, but not in the ordinary work of the draft- 
ing-room. 

In using the horn center, it is placed with its center as 
nearly over the required point as possible, and is pushed down 
until the three points on the under side are firmly imbedded in 
the paper and wood; in other words, it is pushed "home." 
Then, great care must be taken that the point of the compass 
is placed on the horn center directly over the correct point. 

In place of the horn center small pieces of thin transparent 
substances such as isinglas or sheet gelatine are used. These 
have no points on the under side and depend on the friction of 
the paper for their position. These materials are used only 
when an especially handsome drawing is to be made and it is 
desired that no holes shall be made in the paper by the points 
of the horn center.' Ordinarily the horn center is used. 

To Use Isinglas or Sheet Gelatine. — Cut up into pieces 
about yi'' square. Make a hole in the middle with a shouldered 
needle and turn the needle a few times so it will be loose ; 
moisten the under side of the isinglas until it is quite soft ; then 
press it on the spot where required, using the projecting needle- 
point as a guide; press it hard against the paper until it 
adheres ; remove the needle-point ; and then with the agate 
polisher press the surface of the isinglas center down until it is 
flush with the surface of the paper. This prevents the T square 
from lifting it from its position. 

Brushes. — These are of camel's hair. Their uses are 
described under "Shading." 

Pricker. — This is practically a needle-point set in a handle, 
and is made of various forms. It is used in marking off 
dimensions. 

Beam-compasses or Trams. — These are flat, wooden rods 
of various lengths with two clamps that may be secured at any 
points of the length. One clamp contains a "center," and 
the other either a pencil- or pen-point. They are used for 
drawing large arcs. 



30 MECHANICAL DRAWING. 

Foot Rule. — This is used in sketching, dimensions taken 
to the nearest thirty-second. 

Calipers. — These are of two kinds, outside and inside, 
used, as the names imply, for measuring- outside and inside 
distances when a rule cannot be used. They are used particu- 
larly for finding the diameters of cylinders. 

In measuring the diameter of a cylinder use the bent 
calipers ; open the calipers until they are slightly larger than 
the diameter of the cylinder; bring them to the diameter by 
gently tapping them on the outside or inside of the legs as 
necessary. Hold the calipers loosely in the fingers and as 
nearly as possible at right angles to the Avork being measured, 
and above the work if possible, so that the calipers will them- 
selves assume the position where the measurement is least. 
Raise and lower them slowly and adjust them until a very 
slight touch is obtained. To measure the distance thus found, 
place the calipers on the foot rule with the flat face at the end 
of one leg just against the end of the rule and in line with the 
marks for the sixteenths ; the measurement may be read from 
the flat face of the other leg. 

The inside calipers are the straighter ones and are used in 
the same way in the interior of an opening, but the flat surfaces 
at the ends of the legs are now facing away from each other. 
To measure the distance found, lay the calipers on the foot rule 
so that the flat face at the end of one leg rests along the side 
of the rule and in line with the marks for the sixteenths and at 
one of the inch-marks ; the measurement is read from the flat 
face at the end of the other leg. It is best not to bring the 
first leg to the end of the rule, as it is difficult to determine 
when it exactly agrees with the edge. By standing rule and 
calipers on a flat surface, of course, the edge may be used, 
but the other method is sufficiently accurate. It is found that 
the sense of touch becomes rapidly and accurately developed 
in using the calipers, and that dimensions found in this way 
are reliable. 




USE OF INSTRUMENTS. 31 

Splines. — These are thin strips of wood or rubber that are 
held in place by weights, and are used for drawing 
irregular curves when they are long and it is not 
convenient to use the irregular curves furnished. 
The section of the spline is shown in Fig. 13. 

Spline-weights of lead with metal projecting 
wires called ' ' fingers ' ' are used for holding the 
splines. The fingers project from the ends of the weights, 
and the ends of the fingers are thinned and fit into the space in 
the top of the splines, thus holding the easily bent splines in 
any desired position. This leaves the surface of the spline 
away from the weights free, so that this edge may be fitted 
to any curve and lines may be drawn. 

Lead-wire, — This is used for sketching whenever a peculiar 
contour is to be copied. The wire is bent to fit the outline to 
be copied, and marks are made at certain fixed points that may 
be found on the drawing-board. The wire is carried to the 
board and the outline copied. These are used only in one 
plane. 

Paper-cutters. — These are special devices for cutting the 
paper from the drawing-board, but the knife answers all pur- 
poses. 



GENERAL DIRECTIONS. 



Stretching Paper. — For ordinary work, the paper is 
secured on the drawing-board with thumb-tacks, as described. 
For compHcated drawings and for those to be tinted, the paper 
is stretched on the board. 

Prepare the drawing-board by removing all old paper and 
glue, and see that the surface where the paper is to be placed 
is smooth and has no holes. 

Raise the sheet of paper and look through it to the light 
and find the water-mark or other mark of the manufacturer. 
When the paper is held so that the name may be read properly, 
the nearest surface of the paper is the one on which to draw. 
Lay the paper drawing side up on the drawing-board. At 




Fig. 14. Fig. 15. 

each corner either make a diagonal cut about an inch long, as 
in Fig. 14, or cut out a small square about three-quarters of 
an inch either way, as in Fig. 15. 

With the fingers, turn up the edges of the paper along one 
of the longer sides about ^"; repeat on the other longer side; 
then turn up the narrow edges in the same manner. Turn the 
paper over and let it rest on these edges. With a sponge or 

32 



GENERAL DIRECTIONS. 33 

damp cloth thoroughly moisten the paper except the edges 
now turned down. The paper will absorb a large amount of 
water. The object is to have the paper equally wet all over, 
and especial care must be taken to moisten the corners. 
Carefully keep the bent edges dry. After the paper is soaked 
well, turn it over and place it in the most central part of the 
board. With a brush lay the paste or other adhering sub- 
stance evenly along the turned edge of one of the longer sides 
of the paper. A paste made of dextrine and water is excellent 
when the board is unvarished. Press this edge firmly dow^n 
on the wood, rubbing it along from the center to either edge 
with the fingers or a smooth substance. This tends to stretch 
this edge somewhat. Treat the edge of the opposite longer 
side of the paper with the paste and lay that down as before. 
After this edge has begun to stick, begin at the middle of the 
length and draw on the edge with the fingers, endeavoring to 
stretch it tauter by pulling directly away from the edge already 
pasted, constantly, at the same time advancing the hands from 
the center towards one edge, while holding fast all the stretch 
obtained. Then work from the center towards the other edge. 
The object is to stretch the paper across the board and at the 
same time to stretch the edge lengthwise. After this edge is 
pasted, treat the sides in the same manner. 

After this go over the entire board and draw the edges, 
endeavoring still further to stretch the paper. The point is to 
draw and hold until pasted. Often large wrinkles may be 
drawn out of the paper in this manner. When stretched, leave 
the board in a horizontal position to dry. In a few hours it 
will be found that the paper will be stretched taut. 

A more rapid and very successful method is as follows : 
Place the sheet of paper in a vessel of water and allow it to 
become thoroughly soaked and thus enlarged. Remove the 
paper and allow the loose water to drain off. Place the paper 
on the board right side up. Wipe with a towel or other cloth 
along the edges to be pasted, drying them as much as possible. 



34 MECHANICAL DRAWING. 

Apply the paste and press the paper on the board. No cutting 
of corners is required, and no stretching the paper by pulling 
along the sides. When dry the paper will be well stretched. 

The board with the wet paper should be kept in a horizon- 
tal position until the paper is dry. 

In damp weather the stretched paper may absorb enough 
moisture so that it will again wrinkle, especially in the corners 
where it may not have been sufficiently moistened when 
stretched. In this case, with a knife make cuts along and 
outside of the cutting lines of the paper in the neighborhood of 
the wrinkle. Cut enough so that the paper will lie flat and the 
T square will pass over the wrinkled spot with no trouble. 
The shrinkage of the drawing-boards often causes these 
wrinkles, and it is often necessary to cut lines along the whole 
of the top and bottom of the paper and a short distance up the 
sides before the T square will lie flat. Cut only a small 
amount on the sides and as much on top and bottom as is. 
necessary. Generally it is necessary to cut clear across top 
and bottom. The paper is still stretched by being held at the 
sides, and good work may still be done on it. Never put a 
thumb-tack in the paper where it has been cut as stated above. 
Let it lie flat. 

Profile Drawings. — These drawings are those of figures on 
a plane, and are principally used in Plane Descriptive Geometry 
and for the purpose of learning how to use the various instru- 
ments. The first two drawings are Profile Drawings. 

General Arrangement. — In making drawings of compli- 
cated arrangements of mechanism, as a ship, machinery, pipe- 
lines, turrets, etc., a general plan is first made from the main 
ideas of the results to be accomplished. In the case of the 
ship, the general plan shows the location of the many impor- 
tant parts of the structure, and is made in a very general way 
with no attempt at detail. In the case of a complicated engine, 
the general plan called " General Arrangement of Machinery " 
shows how the machinery is to be assembled after the indi- 



GENERAL DIRECTIONS. 35 

vidual parts are completed. The same applies to the turret, 
the positions of the various mechanisms, guns, rammers, 
elevating-devices, etc., being shown. 

In these general arrangements only the principal dimen- 
sions are given, so that, when each portion is completed, it 
may be secured in its proper place. There is no detail, though 
the general appearance of the details may be drawn. 

Working Drawings. — After the general arrangement is 
■completed, working drawings are made of the various portions 
that make up the complete mechanism. Each portion is 
drawn in the minutest detail, so that the many workmen em- 
ployed in manufacturing the various articles may be able clearly 
to understand how each one is to be manufactured. As many 
views as are necessary to a thorough understanding of the 
subject must be made. It is not sufficient to make the views 
to an exact size on an exact scale ; dimensions must be placed 
on the working drawings so that it will not be necessary for 
the workmen to use a rule in order to determine the size of any 
important part or minor detail of the piece worked upon. 
These dimensions must be clearly placed on the drawing. 

Working drawings are sometimes made on white paper in 
pencil, inked and finished, and then varnished and sent 
directly to the shops. Sometimes they are finished as before 
and are then traced and blue-printed and then sent to the 
shops. They are traced by placing over them a transparent 
paper or cloth and a copy made. These drawings on trans- 
parent cloth or paper are then treated as films used in cameras 
and prints are made. Generally blue-prints are used. The 
great advantage of tracing and blue-printing is that as many 
prints as desired may be made. 

The business method at present is to make the drawing in 
pencil on white or on cheaper brown drawing-paper and then 
to trace directly from the pencil-work, the tracing being 
the only finished drawing made. This tracing is then the 
^' original ' ' and is carefully preserved, while the pencil drawing 



36 MECHANICAL DRAWING. 

is destroyed. In this case the pencilled drawing is completed r 
dimensions, legend, etc., but no shade lines or hatching. 

Before giving the method of procedure in making drawings, 
certain methods used will be explained. These should be 
referred to when drawings are being made as the need of using 
each one appears. 

Views. — In general, mechanical drawing of the practical 
kind requires only orthographic projections — those where the 
rays of light are all parallel for each view of an object and 
where all lines are represented full size or to scale. In order 
to show an object clearly by mechanical drawing, it may be 
necessary to make several views of the object. These views 
are taken from positions at right angles with each other. The 
first view to be considered is the Plan. The object may be 
supposed to rest on the drawing-board or the ground, and the 
draftsman is directly over each point of the object and en- 
deavors to represent the object on paper as it appears to him 
from his point of view. Measurements are taken and the 
object drawn. 

The next view to consider is the Front Elevation. Leav- 
ing the object in its position, the draftsman moves to one side 
— generally the longest side — -and is supposed to have his' eye 
for each point of the object in a direction at right angles to the 
vertical and at right angles to the central plane of the Plan 
view. He takes measurements from this point of view and 
draws the object as it appears to him. 

The next view is the Side or End Elevation. The object 
remains as before and the draftsman moves to one end — 
generally to the end on the right of his position for the Front 
Elevation — where, for each point of the object, his eye is sup- 
posed to be in a direction at right angles to the central planes 
of both the Plan and the Front Elevation. He takes measure- 
ments and draws the object as it appears from that point of view. 

These three are the views generally taken ; in a few cases, 
where the object has a complicated structure, it may be neces- 



GENERAL DIRECTIONS. 



17 



sary to draw the other End or Front Elevation and occasionally 
it may be necessary to draw a Bottom View, as though the 
draftsman were underneath. In that case the object is turned 
bottom up while the dimensions are taken, if possible. 



Another way to look at this method of making the different 
views is to first consider the object resting as before and draw 
the Plan. Then consider that the object is tipped over 
through an angle of 90°, the top moving away from the drafts- 
man as he stands in position for drawing the Front Elevation ; 
by placing "the eye directly over the object in the new position, 
a drawing may be made as for the original Plan. For the end 
view, the object in its position for Front Elevation may be 
considered to be tipped over through an angle of 90°, the top 
moving to the left of the draftsman as he stands in position for 
drawing the Front Elevation; by placing the eye directly over 
the object in the new position a drawing may be made as for 
the original Plan. 

The other Side Elevation, Front Elevation, and Bottom 
View may be considered in the same manner, by revolving the 
object as required in each case. 




Fig. 16. 



38 MECHANICAL DRAWING. 

Another method. — Imagine the object partly surrounded 
by three transparent planes A, B, C, and that on each plane is 
projected an outline of the object, bringing the Plan or top 
view on plane A, the Front Elevation on plane B, and the Side 
Elevation on plane C. Flatten out these planes by separating 
two of them along the edge hn and moving them in the direc- 
tions shown by the arrows, and the views will be arranged as 
shown to the right. 



Besides these views it may often be necessary to make 
other special views of the object, or special sections, or special 
enlarged views of minor parts of the mechanism. These may 
be placed on the board according to judgment; as a rule, 
however, it is well to place these lesser views as near their 
position on the larger views as possible. 

The views need not be drawn in the order given, as it may 
very much simplify the work if the Front or Side Elevation is 
drawn first. 

The method of arranging the views is as follows : 

Plan. 

Side Elevation. P'ront Elevation. Side Elevation. 

Bottom View. 

As the Bottom View is seldom required and one of the 
Side Elevations generally suffices, the ordinary arrangement 
is as follows : 

Plan. 

Front Elevation. Side Elevation. 

Projections. — In describing the method of considering the 
object as revolved through angles of 90°, it will be noted that 
each point of the object moves in a plane and keeps its same 
relative position from any edge that it had originally. 

Consider the Plan as drawn and place the object over the 
drawing. It will of course exactly cover the lines drawn. 



GENERAL DIRECTIONS. 



39 



Revolve the object for the Front Elevation — -that is, so that 
the top moves up the drawing-board — and it will rest on its 
side above the Plan. Draw the object directly down the board 
until below the Plan with any desired amount of space between. 
Measure the object as it appears from a point directly over it ; 
remove the object and make the drawing. It will appear as 






6'c 






a b 



-f-m 



Fig. 17. 

shown in the Front Elevation. In this case the narrow side 
is taken for the Front Elevation. Note that each point of the 
object described a line in a vertical plane or one up and down 
the board, as it was revolved; and that the pointy was drawn 
along, after being revolved, in a vertical direction or along the 
drawing-board, so that the point always remained in the same 
plane; and the plane was certain to contain the point no matter 
at what part of its revolution or movement vertically. Then 
draw dotted lines vertically from any points, as a, b, c, d, to 
represent these planes, and the points will at all parts of the 
movement be somewhere in the planes represented by these 
line'5. 

In the same manner take the object as resting on the Front 
Elevation and revolve it to the left and then draw it along the 



40 MECHANICAL DKAWING. 

paper to a convenient distance to the right. Again, these 
points, a, d, c, d, etc., will revolve in a plane, and a horizontal 
line will represent the plane in which they move. As they 
are all in the same plane, one dotted line represents the one 
plane in which they all lie. The point which was revolved to 
a' now falls at a" ; b, which was projected to b' , now falls at 
//'; c, at c' and c" ; d, at d' and d", etc. ; b" and d" fall at 
the same point; also c" and e" . 

These are called the projections of the point. There are 
many methods of describing how to make projections, but this, 
method explains how they are used in practice on the drawing- 
board. 

Another method of projecting the points from the Plan to 
the Side Elevation is shown in Fig. 17. After the Front 
Elevation has been drawn by projecting from the Plan as far 
as possible and finishing by putting in the other lines as 
measured, the line kl is taken, at any convenient distance from 
the Front Elevation, as the side line for the Side Elevation. 
Extend the line kl upwards and project on this line the points 
of the Plan that are needed in order to draw the Side Elevation. 
On -^ as a center, swing these points down to the line km and 
project them from this line to the Side Elevation. 

This method is more of a Descriptive Geometry one than 
a drafting-room method (though it is sometimes necessary 
there), and should not be followed as a rule. 

Distances are seldom measured more than once on a draw- 
ing if they can be readily projected. 

Lines. — There are three kinds used in Mechanical Draw- 
ing: full, broken, and dotted. 

The full line is a continuous line. The full line in black 
ink is used to show any edge or boundary of a surface when 
the edge is in sight from the point of view from which 
the drawing is made. The full lines in red ink are center 
lines. 

The broken line is one composed of short or long dashes. 



GENERAL DIRECTIONS. 4 1 

"with spaces between. The spaces should be about one-fourth 
the length of the dashes. For ordinary work in black ink the 
dashes are about one-eighth of an inch long and the spaces 
about one-thirty-second of an inch in length. These lines are 
as heavy as the full lines of the drawing, as they are equally 
important, but are never made as heavy as shade lines. The 
broken lines in black ink are used to show any edge or 
boundary of a surface when the edge is concealed from view. 

When two broken lines are parallel and close together, 
break joints with dashes and spaces. 

The broken lines in red ink are used for dimension exten- 
sion lines and for dimension lines. The lengths of the dashes 
and spaces vary in this case, as explained under "Dimension 
Lines. " 

The dotted lines in red ink are used for the projection of 
points from one view to another. They are seldom used 
except for the first drawings and when an exceptionally diffi- 
cult intersection is made. 

The dotted line is a series of the shortest dashes that can 
be made, the spaces between being fully as great as the length 
of the dashes, so that the effect is that of a series of dots. 
These dotted lines are always fine lines, as they are subordinate 
lines. 

Broken and dotted lines are never shaded. 

Center Lines. — All drawings of objects are made from 
center lines. These are the first lines drawn in sketching and 
in work on the drawing-board. When an object is to be 
sketched or drawn, it is examined and the necessary views 
decided upon. Next determine the positions of the center lines 
of the object. These lines are as a rule imaginary and pass 
through the center of figure of the body in the three directions 
at right angles to each other, as must ,.be the case from the 
three views generally drawn. If the body is uniform about 
these centers, as a cube, there is no difficulty in determining 
the center lines; if it is a cylindrical body, there is again little 



42 MECHANICAL BRA WING. 

difficulty in placing the center lines ; and so with any body of 
revolution. In most bodies, however, there is some system 
so that the middle of the width of one side may be taken as a 
starting-point in deciding on one center line, and the others 
are arranged to the best advantage. In the case of a cylindrical 
body, measure the diameter with the calipers and the center 
line will be half-way. 

After the center lines are decided upon, measurements are 
made with regard to them and the sketch or drawing con- 
structed from them after they are drawn in. The cylindrical 
part is measured from the center line, the radius laid off either 
way. Distances parallel to the center line are measured along 
that line and vertical lines are drawn through the points 
marked. Then the distances from the center on these vertical 
lines are measured and laid off and the positions of the points 
in that view are established. Each point is in this way 
established in one view and then is projected to another view, 
if possible, so that the least number of measurements may be 
made. 

The positions of the views are given under the neading 
"Views." Next measure the extreme or " over-all dimen- 
sions " of the object and decide on the scale to be used and 
calculate as to where the center lines of the various views must 
be placed. This requires considerable care in order that the 
views may all be placed on the drawing-board without inter- 
fering with each other and so that the points may be properly 
projected for the views. As a rule, the positions of the center 
lines for the Plan, one of which extended will be a center line 
for the Front Elevation as well, are decided upon first, if a 
Plan is to be drawn. After that the positions of the center 
lines of the Front Elevation, one of which will also be a center 
line for the Side Elevation, are decided upon. Then the other 
or vertical center line for the Side Elevation is decided upon. 
All these center lines should be drawn in pencil before any 
work is done on the drawing. 



GENERAL DIRECTION'S. 43 

These center lines should be drawn with the greatest care 
and should be firm, clean lines, as measurements are made 
along and on either side of them, and the accuracy of the work 
depends on the accuracy of the center lines. 

Centre lines are drawn for each view of the object repre- 
sented, and for centers of bolts or bolt-holes and wherever 
centers are used in constructing the drawings. They are inked 
in after the black-ink work is entirely completed, and are drawn 
solid lines in red ink with the lines extending beyond the 
figures for a distance of from y^" to i", depending on the size 
of the figure. The system of extending the center lines until 
they meet other center lines and thus form rectangles is not 
approved. 

Shade Lines. — To give life to a drawing and to make it 
apparently stand out from the paper, shade lines or relief 
lines are used. These distinguish raised and depressed por- 
tions of an object. They are all of the same width and are 
about four times as wide as the original lines ; in tracings they 
are still wider. 

Shade lines are always drawn outside the original lines of 
the figure. The light is supposed to fall on the object in all 
views from the top left-hand (N. W.) direction at an angle of 
45° from above; and, generally speaking, the heavy line marks 
the dividing edge between light and dark surfaces, though it 
often marks edges when both surfaces forming the line are in 
shadow. 

The shade line begins and ends at its full width and does 

not slope at the ends, as, \^; but is drawn % 

The positions of these lines are largely conventional, but 
certain general customs prevail. 

As a rule, the right-hand and lower sides of the figures are 
shaded ; the opposite for interior openings. 

In Fig. i8, y^ shows a central raised portion and B a de- 
pressed interior portion. 



44 



MECHANICAL DRAWING. 



The question of the hnes to be shaded may be studied by 
considering which edges would cast shadows if the object were 
placed so that the light came from the proper direction. 





Fig. i8. 

Place a 60° triangle on the drawing-board in position 
against the T square and then remove the T square. Shadows 
will be found at a, b, and c. Place a 45'' triangle beside the 





Fig. 19. 

60° one and shadows will be found at b and c only. As the 
light now shines along the side a, there is no shadow, and 
hence no shade line. Turn the triangles the other way and 
remove the square and the shadows in both will be found at 




Fig. 20. 

d, e, and/". Now turn the triangles about centers and note 
where the shadows besfin and end on the different interior and 



GENERAL DIRECTIONS. 



45 



exterior edges while the turning slowly proceeds. Since all 
the rays of light are considered parallel and all come from the 
N. W. and from above at an angle of 45°, the shadows begin 
as soon as the direct rays of light fail to strike the edges. 

The edges to have shade lines may generally be readily 
determined by eye, but if an edge away from the source of 
light is nearly in a N. W. direction, the question of the shade 
hne may be determined by placing a 45° triangle in position 
on the T square. If the edge of the solid body farthest from 
the source of light is beyond the 45° point, so that the light 
does not shine along that edge, a shade line should be placed 
on the drawing. 

Cylindrical and other curved surfaces are shaded. 

When circles are shaded, the method given above of 
determining the shaded portions by using the 45° triangles will 
be followed. The shade lines begin at the points where the 
light fails to strike the edges. These points are determined 
by the 45° triangle placed on the T square and held just tan- 
gent to the arc ; but a simpler way is to place the triangle on 
the T square in the reversed position with the diagonal edge 
at the center of the circle 

This edge will be a normal to the tangents at a and b, and 
marks may be made there for the ends of the shade lines. 





Fig. 21. 



For an interior, as the inner line of the hollow cylinder in 
Fig. 21, the opposite part of the arc is shaded; the points 
of beginning and ending are found as before. 

In shading these circles, it is generally customar}^ to taper 



46 



MECHANICAL DRAWING, 



the shade Hne to nothing at a and b and make it heaviest at 
c, the point of broadest shadow. 

There are several methods of drawing these irregular shade 
lines. The best method is as follows (see Fig. 22): After 
drawing the original circle, begin again near a, but between a 
and <:, and slightly spring the compass without changing the 
set of the instrument, following along a line like the outer por- 
tion of the line between a and /?, through c. This requires a 
gradual springing open and a gradual closing of the instru- 





FiG. 22. 



Fig. 23. 



ment, and requires considerable practice before perfect work 
may be done. After the outer line is drawn, the space between 
the lines may be filled in by springing the instrument as 
desired, at the same time opening the pen-points wider. 
Always draw in the same direction, however, returning for 
each new sweep of line. 

The heaviest part of the shade is about four times as heavy 
as the original line, as in the case of the straight lines. 

Another method of drawing shade lines of circles is as 
shown in Fig. 23. 

Begin at the point c near a and draw a heavy shade line 
(four times the width of the ordinary line) to a point d near i . 
From a to c and from 3 to d taper the line by springing the 
instrument as described above. This method is little used. 

For irregular curves or for portions of arcs the points of 
beginning and ending of shade lines are determined, as with 



GENERAL DIRECTIONS. 



A7 



straight lines, by the 45° triangles. In this case, the shading- 
tapers from nothing to the full width, as explained in the 
second method of shading circles. 

Fig. 24 represents a fillet, a small arc of a 
circle joining two straight lines. The point of 

beginning the shade is determined by the 45° 

Fig. 24. triangle set at the center of the arc, and the shading 
is gradual up to the point of meeting the straight line. 

Fig. 25 represents a curved surface like a section of a por- 




FiG. 25. 

tion of a cylinder-head. The shading is shown. Note that 
the shade lines cross the figure at the 45° points. 

When surfaces of separate portions of the figures are touch- 
ing and are at the same level, no shade lines are drawn. 



1 

a ^ 


2 


c 








2 


la 6 



b 2 



a 


2 





5 2 



Jd 



Fig. 26. 



In A and A', Fig. 26, block i is wider and lower than 
block 2. In the top figure or plan view, when looking down 



48 



MECHANICAL DRA WING. 



on the blocks, the sides a, c, and d are shaded in accordance 
with the general plan ; the line b is shaded only where it is 
free from block 2, as its edge in contact with block 2 cannot 
cast a shadow. In the lower figure or elevation, when looking 
at the side of the blocks, a, c, and d are shaded by the general 
plan, and b is shaded as it projects beyond the block 2. 

In figures B and B' , where the blocks are equally high and 
wide, there is no shade line at b in either view, as the edges 
are on the same level. 

In figures C and C, block 2 is lower and wider than 
block I. In the top or plan view, when looking down on the 
blocks, the sides a, c, and d are shaded by the general plan 
and b is shaded where block i is higher than block 2, as it 
may there cast a shadow ; but the remainder of the line — that 
for block 2 only — is not shaded, as the light may strike that 
edge. 

In the lower view, or elevation, when looking at the side 
of the blocks, the lines a, c, and d are shaded by the general 
plan, and b is shaded only where block i is above block 2. 

As seen above, in shading one view of an object, it is often 
necessary to refer to the other views. 

The shade lines are drawn outside the original lines so that 



^ i- 




FiG. 27. 



the inner dimensions may be retained and measurements 
accurately taken. This method also allows placing the arrow- 



GENERAL DIRECTIONS. 



49 



points used for marking the dimensions so that they just touch 
the inner edges of the figures, as in Fig. 27. 

All the shade lines should be of the same width. Make a 
sample line on the border of the paper and often test the set 
of the pen with this sample line. 

Shade lines are not shown in the pencil drawings. 

Dotted or broken lines are never shaded. 

Bolt-heads are shaded in various ways, but the best method 
is shown in Fig. 28. It will be observed that the general plan 
is followed. 

— \ 



i 



Fig. 2S 



Where a bolt, rod, rivet, etc., is represented in elevation 
resting in a section, the shading conforms to the method shown 
in Fig. 29. 




Fig. 29. 

Shade a, keeping outside the head of the rivet. 
Shade b, keeping outside the rivet. 
Shade c, keeping outside the plate. 
Shade d, keeping outside the section. 
Shafts and other Cylindrical Objects. — In representing 
these on the drawing-board, it is best always to draw first the 



50 



MECHANICAL DRAWING. 



view that shows the shaft as a circle. Measure off the radius; 
from the center and strike in the circle. For the other views, 




Fig. 30. 

the straight lines may be projected from the arcs and time will 
be saved. 

Sections. — If an object is cut through by an imaginary 
plane in any direction, the drawing showing the appearance of 
this imaginary cut is called a section. (See models of sec- 
tions.) 

The draftsman is supposed to be in a position normal to 
this cutting plane, and to draw what appears from that point of 
view. 

Sections are drawn to show clearly a hollow interior or to 
clear up any part of the drawing that is not lucid from the 
other views, and considerable choice may be made in the posi- 
tions of the cutting planes chosen. These are, however, 
usually taken either vertically or horizontally, though they are 
sometimes taken in other directions ; but they are generally 
perpendicular to either a vertical or horizontal plane. Often 
a vertical plane is passed through on a radius on the Plan, and 
the section is swung around until it coincides with the plane of 
the paper, when it is drawn. 

When a section is made, the drawing must show not only 
the part of the object in the plane, but everything beyond to 
the end of the figure. 

Those parts concealed by the figure are drawn in broken 
lines. Sometimes portions of the object beyond the section 
plane may be omitted when the drawing would be too compli- 
cated ; the main outlines are always drawn. 

In making a Plan or Elevation, it is sometimes well to 



GENERAL DIRECTIONS. 51 

make part of a view a section ; or to remove a portion of the 
object to more clearly show the interior. In this case, the line 
of demarkation is always a solid black line made with the 
right-line pen, and is generally straight. This line is shaded 
in accordance with the directions under " Shading." 

If a section is made at any plane, a heavy, broken red 
line is drawn at that plane, and its extremities are marked 

A, . . . . .B, C D, etc., and the drawing of the section 

is clearly marked, Section AB, Section CD, etc. ; or. Section 
on AB; or. Section on line AB. 

The section drawn may not follow a plane, but may run 
irregularly across the figure ; the broken red line will follow 
the course of the section, however, so that its course may be 
clearly marked. 

Hatching. — ^In making a drawing of a section, the por- 
tions where the plane passes through solid substances are 
"hatched." This consists in covering these portions of the 
surface with lines of various kinds, to represent the fact that 
solid substance is cut; and also to represent, according to 
accepted methods, the kind of substance that is cut by the 
plane. (See drawing of Standard Hatching at end of book.) 

Hatching is never drawn in pencil ; in black ink only. 

The lines of hatching are of various widths apart, according 
to the size of the surface to be covered. For small surfaces 
the lines are quite close together, as in F'ig. 31. 



m. 



Fig. 31. 

For larger surfaces the distance apart of the lines increases, 
until, for a very large surface, the lines may be as in Fig. 32. 

It is also customary in making sectional views of very large 
surfaces to begin the hatching away from the edges, as shown 
in Fig. 33. 



52 



MECHANICAL DRA WING. 



Still another custom, for reduction of the work of hatching 
large surfaces, is shown in Fig. 34. 




Fig. 32. 




Fig. 33. 




Fig. 34. 

These last two conventions are used especially in drawings 
of embankments, etc. In machine drawings these methods 
are seldom necessary. 

The lines for hatching are drawn with the 45° triangle as 
long as that angle can be used, the first ones used being 
always the lines from S. W. to N. E. on the board. When 
two surfaces cut by the plane of section join along a line, one 
of the sets of lines for hatching must be inclined one way 45° 
and the other one the other way 45°, so as to distinguish 



GENERAL DIRECTIONS. 



53 



the separate pieces readily. A third substance in contact with 
either of these two must have hatched hnes at another angle; 
a fourth at still a different angle, etc. After the two 45° lines 
have been used, it is customary to draw the others that are 
necessary with the 60° tiiangle. 

After the drawing is inked and dimensioned, the hatching 
is done. Set the pen to make clear lines, not too fine; decide 
on the angle of the lines and their distance apart; with the tri- 
angle at the correct angle begin at the portion of the surface 
to be covered that will allow the triangle, as it moves back for 
the hatching, to sweep from end to end of the surface; space 
the distance apart by eye and do not try to get a certain number 
of lines per inch. Do not attempt to have the lines come out 
even at any point; the distance apart is what is important; 
cover the entire surface that belongs to the same body with 
lines at the same angle and the same distance apart. 

Hatching machines of various kinds are a mistake for 
beginners. A steady hand and a quick eye will soon cause 
proficiency, and the training is excellent. 

When two surfaces of about the same size and the same 
material meet at a line and both are to be hatched, finish one 
hatching, and draw the other so that the various lines meet 
the first set of lines at the line of demarkation, as in Fig. 35. 





Fig. 35. 



Fig. 36. 



Another method that emphasizes the line of separation of 
the surfaces is shown in Fig. 36. 

When the sketching consists of heavy and light lines, the 
surface is hatched across with the light lines as though those 
lines were the only ones to be used. The correct spaces are 
then filled in solid, producing the heavy lines. 



54 



MECHANICAL DRAWING. 



To fill in these spaces, draw a fairly heavy line on either 
side of the space to be filled; go over all the spaces of any one 
portion of metal and allow these lines to become dry; then 
open the pen wider and fill in the central portions. These 
filling lines are drawn with the R. L. pen guided by the tri- 
angle. Never fill in with a writing-pen or use the R. L. pen 
as a brush. 

This method of filling the spaces causes a loss of time, as 
the first lines drawn must be allowed to dry, but the method 
is a safe one. A more rapid method and a better one after 
sufficient experience has been acquired is to fill each of the 
spaces at once by drawing line after line until the surface of 
the space is covered with liquid ink. The ink will then dry 
evenly over the entire surface of the space. Also, this allows 
of continual advancement without waiting for lines to dry. 
Caution is necessary to keep the triangle well away from the 
liquid lines of ink or a bad blot will result. 

Just as good ink-lines are reqidred for hatcJiing as for the 
other parts of the drawing. Do not attempt to make the lines 
of hatching too fine. 

In doing hatching, glance back after drawing every ten lines 




Fig. 37. 

or so to see that the spacing continues regular ; if irregular, 
gradually change the spacing until the exact amount is 
obtained. 

In drawing sections where the plane passes through the 
center line of a cylindrical body, the cylinder is generally not 



GENERAL DIRECTIONS. 



55 



hatched, but is drawn in elevation, resting in the section. 
This refers to shafts, spindles, bolts, rivets, etc., as in Fig. 37. 
Fig. 38 shows a Plan and Elevation of a steam-cylinder. 
The Plan is half in section, the section taken at the line AB 
of the Elevation. The upper half of the half-cylinder is 
removed and the section drawn, the lower flange of the 




— D 






^^z^ 



Fig. 38. 

cylinder showing below the section. Each bolt-hole is drawn, 
and the centers marked, first by the circular center line and 
also by the short radial lines. 

The elevation of the cylinder is also half in section, the 
section made at the plane CD in the Plan. In this case the 
front half of the half-cylinder is removed and the section 
drawn. The top and bottom lines of the flanges and the 
opening at the bottom are carried across to the center line. 
The lower line of the upper flange in the section is a broken 
hne, as this rim of the flange is concealed behind the section. 



56 MECHANICAL DRA WING. 

The lines at the opening in the bottom of the cyhnder are both 
full lines, as the edges of the opening are in view though both 
the lines drop away from the plane of the section. 

Besides the main center lines for both figures there are 
drawn in the Plan the circular center line and the short radial 
dashes for the bolt-holes, and in the Elevation the short center 
lines for the bolt-holes. In the Elevation only the bolt-hole 
at the diameter is dotted in the outside view, and drawn full in 
the section. The other bolt-holes are shown sufficiently in 
the Plan. The hole in the bottom of the cylinder is shown in 
the Elevation, one edge drawn full in the section, and the other 
a broken line. The lines in both Plan and Elevation separat- 
ing the section from the other view are drawn full black lines ; 
their extensions, the center lines extended, are drawn in red 
ink. These black division lines are shade lines as explained 
under the heading "Shade Lines." 

Breaks. — Breaks are used in drawings to represent that a 
shaft, rod, etc., is broken off. This is done when there is not 
enough space on the paper to draw in full length any portion 
of the mechanism, or when it is undesirable and unnecessary 
to use the space required for the purpose. These breaks are 
also used to show the shape of the cross-section and the kind 
of material of which it is composed. They are complete in one 
view and have no reference to any other view. 



^£E 



k- 3f^_ ^ 

Fig. 39. 

The irregular lines of fracture are made in black ink and 
are drawn best with the R. L. pen held carefully and twisted 
in the fingers, so as to keep the nibs always parallel with the 
line of direction of the movement. One of these lines is a 
shade line throughout ; the other a light line. This adds mucli 
to the effect. 



GENERAL DIRECTIONS. 



57 



The rod must always be broken as shown, so that a piece 
is lost from the central portion and the ends left intact. In 
this way the total length or ' ' over-all dimension ' ' may be 
eriven. 



^ 16'^ >j 

Fig. 40. 

A variation is sometimes made in the method of making 
the break, as shown in Fig. 40. This shows the material, the 
hatching being done in accordance with the "Standard 
Hatching. " 

Often breaks are made of small portions of a piece of 
mechanism in company with a portion of a section, as shown 
in Fig. 41. 




Fig. 41. 

In order to show the kinds of metals, and to make more 
clear the interior of the mechanism, the irregular break is 
made. It is considered that this break extends inward to the 
center line and that the top half is removed. This irregular 
break is drawn as before with a R. L. pen used carefully. 

Dimension Lines. Dimension Extension Lines. — Besides 
drawing the views of an object to correct size or to a certain 
scale, the dimensions of all parts of the object must be clearly 
placed on some of the different views, so that whoever may 



58 



MECHANICAL DRAWING. 



have occasion to use the drawing will not be obliged to measure 
any dimension. 

Auxiliary lines are used for these dimensions. They are 
light, broken lines in red ink and are drawn after the center 
lines are completed. The lengths of the dashes vary with the 
lengths of the lines. 

When the dimension between two points is to be given, 
a red, broken line is drawn from one point to the other, 
leaving a break near the center for placing the dimension. 
This line is drawn directly to the points and terminates at 
these points. The dimension is placed in the space left, and 
at the ends of the line are placed arrow-points, the points of 
the arrows exactly at the extremities between which the 
dimension is taken. See Fig. 42. 



2j.___|.. 



Fig. 42. 

Frequently dimensions are given directly on the views of 
the object; but when this method crowds the drawing, the 
dimensions are placed beyond the outlines, and the distance 
to be marked is carred out from the outlines by dimension 
extension lines, as in Fig. 43. 




Fig. 43. 

The position of the dimension lines is a matter of judgment, 
but the greatest care must be exercised not to complicate the 



GENERAL DIRECTIONS. 



59 



drawing and not to repeat the dimensions on the different 
views unless this may make a complicated drawing easier to 
follow. 

Where two views are beside each other, corresponding 
points are often connected by dimension extension lines and 
the dimension lines drawn between these, as in Fig. 44. 



Lj_ 



Fig. 44. 

When dimension lines are outside of the views, these lines 
are placed at least y^^' away from the outlines of the figures. 

Center lines are never used for dimension lines, and the 
figures for the dimensions are not made over the center lines. 
The center lines are left as clear as possible. 

If it can be arranged without too much difficulty, dimen- 
sions are not placed on hatched portions of the drawing ; but, 
if it is necessary to do this, leave irregular spaces in the hatch- 
ing so that the dimensions may be placed at these points. 

Group dimensions that are for portions of the drawings that 
are alike; that is, place them near together. 

"Over-all dimensions" should always be given for con- 
venience in getting out material for work. This means the 
dimensions of the greatest limits of the object in the directions 



k — — 4e— -^^ -^h — 



Fig. 45. 

of the three center lines at right angles. These are generally 

outside of the figures and should be beyond all the other 

dimensions that are outside the figures, as in Figs. 43 and 45. 

The figures for the dimensions are placed so as to be read from 



6o 



MECHANICAL DRAWING. 



the bottom or right-hand side of the drawing-board. They are 
placed so that the middles of the figures and the horizontal 
line of the fractions are in line with the dimension line ; and the 
figures are at right angles to the line. As the dimension lines 
are drawn before the figures are made, spaces must be left 
while drawing the dimension lines. This requires especial 
care in dimensioning diameters of circles, as in Fig. 46. 





Fig. 46. 



Fig. 47. 



All the dimension lines are in the two quadrants, as shown. 

Diameters, not radii, are dimensioned where possible. If 
radii must be dimensioned, place the arrow-heads at both 
center and circumference, as in Fig. 47. 

Dimension extension lines are broken lines made with red 
ink and extend a short distance beyond the points where the 
dimension arrows are placed. See sketches 43 and 45. 

The dimension and dimension extension lines are made 
with dashes from y^" to ^" long, depending on the lengths 
of the lines. The spaces between the dashes vary from gL" 
to y\"- These lines are never heavy lines. 

Arrow-points are drawn in black ink with a fine writing- 
pen — not with the R. L. pen — and the points of the arrows 
touch the lines between which the dimension is to be given 
The diverging lines of the arrow-heads make an angle of about 
60° with each other. These diverging lines are light, clean 
lines from i/ie" to V^" long. 



GENERAL DIRECTIONS. 6 1 

When the distances are small, these arrow-heads are placed 
on the outsides of the lines, pointing towards each other, and 
the dimension is either placed between the points or is carried 
to one side with an arrow pointing towards it from the space 
to be measured. See Fig. 43. 

The figures for marking the dimensions are made in black 
ink with a writing-pen that is not too fine. They are made 
clear and prominent. The shorter dimensions must have as 
prominent figures as the large ones. These figures are yi" 
high and stand at right angles to the dimension lines. When 
fractions are used, the line separating the numerator and 
denominator is horizontal, as f , not %/\". When mixed 
numbers are used, the inch sign is placed after the fraction, as 
2|", not 2"|. 

When dimensions are given in decimals, the inch sign (") 
is placed over the zero mark; as, 2''375, not 2.375". 

Up to and inclusive of 24", dimensions are given in inches; 
beyond 24'^ the dimensions are given in feet and inches. For 
feet use " ft. " or " feet, ' ' instead of the character ' ; as, 2 ft. 6". 

Dimensions are given in feet, inches, and fractions of 
inches. The fractions of inches used are halves, quarters, 
eighths, sixteenths, thirty-seconds, and occasionally sixty- 
fourths. Fractions are always reduced to their lowest terms. 
The total height of the fraction is about i^". 

The diameters of cylinders and strokes of engines are given 
in inches. These are practically the only exceptions to the 
above. 

In locating bolts or holes, if they are uniform on both sides 
of the center line, draw a circle in red ink through the centers 
and give the diameter of this "bolt circle." This gives the 
distance between the centers of opposite bolt-holes and thus 
the radius of the bolt circle. Mark the center of each bolt- 
hole with a short radial line in red ink. 

If they are not uniform, give the distance from the center 
line to the center of the bolts. Occasionally it is necessary to 



6 2 ME CHA NIC A L DRA WING. 

give the distance between the center of the bolt or hole and 
the nearest edge of the object; but, in general, distances 
should be given from the center lines. See Fig. 48. 




Fjg. 

The number of bolt-holes defines the angular distance apart.. 

On the di^awing-board do not draw the dimension exten- 
sion lines and dimension lines in pencil, and do not put down, 
the dimensions in pencil unless a tracing is to be made from 
the pencilled work. This is all done in ink after the drawing 
is completed. 

On the drawing-board draw first the dimension lines and 
then the arrows ; this is reversed in sketching. 

Threads. — The screw-thread cut on a bolt is for the pur- 
pose of allowing the bolt to advance in the hole as it is turned 
around. As the bolt turns around once it advances a certain 
distance, called the "pitch" of the thread. The nut that 
may turn on the bolt has a thread cut on the inside with the 
same pitch as the thread on the outside of the bolt. The 
thread cut on the bolt is called a " male " thread, and that in 
the nut a "female " thread. 

If we follow the top of an ordinary screw-thread around the 
bolt, we find that for a complete revolution we have advanced 
one thread. Hold the. bolt in a vertical position and the front 
elevation of the bolt shows that the view of the path of the 
point we followed is a curve. This curve slopes upward from 
left to right and then passes behind the bolt and slopes upward 
from right to left; it reappears at the top of the next thread. 



GENERAL DIRECTIONS. 



63 



Thus we have advanced one pitch. In half the revolution one 
half pitch was advanced. The same happens if we follow the 
path of the bottom of the thread. 

To represent the threads on the drawing-board, draw the 
center line and draw parallel to it lines for the outside diameter 
of the bolt. 




Fig. 49. 



Lay off" on the left side the pitch lengths ab, be, cd, etc., 
and the half-pitch lengths at i, 2, 3, etc. Draw horizontal 
lines through these points. Then the top of one of the threads 
will be represented by the curved line from a to a' , as the dis- 
tance travelled longitudinally for one half-revolution will be one 
half- pitch. The other half of the revolution will cause the top 
of the thread to travel behind the bolt in a line represented by 
the dotted line a'b. The other tops of the threads will be 
parallel to these two lines, as the same cycle is repeated 
farther along the bolt. 

The thread represented is called a triangular thread, and 
the standard angle for the sides of the thread is 60°. From 



64 



MECHANICAL DRAWIA'G, 



the points a and b draw 60° lines to meet on the line of half- 
pitch at e. This, then, is the position of the beginning of the 
root of the thread. The root will advance to e' in one half- 
revolution and the moving point will follow the curved line ee' . 
During the other half-revolution this point will follow the 
curved line e'f behind the bolt. These lines, aa'b and ee'f, 
represent, then, the form of one thread for one revolution. As 
the other threads are exactly the same, they are simply copies 
of this first one. 

The curves made are readily found, as they are helices, 
and for every portion of a revolution an equal portion of the 
total pitch is passed over longitudinally. 

It is customary to shade the bottom of the thread, as in 
Fig. 50. The rest is shaded according to the general plan. 

In making drawings, these lines are seldom drawn as 
curves. They are so near straight lines that they are usually 
represented as straight. Fig. 50 shows the appearance of the 




Fig. 50. 



Fig. 51. 



threads as drawn when threads are represented at all. 

The straight lines simply replace the curved ones, and the 
broken lines are not drawn. 

To still further simplify the representation of threads the 
portion to be threaded is shown as in Fig. 5 i. 

The finer lines, i i, 22, etc., represent the tops, and the 
heavy lines the bottoms, of the threads. The distance apart 



GENERAL DIRECTIONS. 65 

of the lines is not measured, but is spaced by eye as in hatch- 
ing. This distance varies for different diameters, being smaller 
for small bolts to represent approximately the number of 
threads per inch of length. 

The finer lines are drawn first. In order that the heavy 
lines may begin and end uniformly, draw fine pencil-lines on 
either side and equally distant from the side lines of the bolts, 
as ab, cd. Draw the heavy lines with these lines for guides 
for the beginning and ending, and place them by eye in the 
middle between the light lines. 

To still further simplify the representation, sometimes the 
heavy lines are omitted entirely, but this is not customary 
except for very small bolts. 

To find accurately the angle at which to draw these repre- 
sentative lines it is first necessary to know the number of 
threads to the inch. 

If the drawing is made from a model, lay a rule along the 
top of the thread so that one ridge corresponds with any inch- 
mark of the rule. Count the number of ridges for one inch of 
length. If the number is 6, 8, 10, etc., this gives the fraction 
of an inch occupied by the length of one thread, or the pitch. 
If there is no model and the bolt is standard, consult a Table 
of Standard Bolts and Nuts, which will give the number of 
threads per inch for the diameter of bolt required. 

A Table of Standard Bolts and Nuts for the United States 
Navy is found at the end of the book. 

Lay off this length on the left side of the bolt and draw 
two horizontal lines through the marks. Since the thread 
must advance longitudinally one-half of one of these divisions 
for the half revolution, one-half this height will show the limit- 
ing height of the right-hand end of the line. See Fig. 52. 

The lines through a and b are apart a distance equal to the 
pitch. The line through c is at the half-pitch. Then ad is 
the line sought. 

As a rule, the slope of the line may be determined with 



66 



MECHA NIC A L DRA WING. 



sufficient accuracy by eye. As the height of this Hne longi- 
tudinally is one half-pitch, double this height must separate 
the lines longitudinally. See Fig. 53. 

After drawing ad with the slope determined by eye, project 
d across to b-y double ab\ ac is the pitch, and the next line 
begins at c. 





Fig. 52. 



Fig. 53. 



After having determined the position of the lines for the 
top of the thread the lines for the bottom may be drawn as 
above. 

When a bolt is turned to the right, or so that the top of a 
thread moves to the right and down, or in the direction of the 
hands of a watch, the thread on the bolt is called a "right- 
handed thread." All of those drawn are right-handed. The 
slope is the opposite for the "left-handed thread." These 
left-handed threads are used only for special purposes. 

When a section is cut through the center of a threaded 
hole, the part of the female thread seen beyond the section 
corresponds to the hidden part of the thread on a bolt, and the 
slope is in the opposite direction. The shading of the female 
thread is the same as that of the male thread, the heavy line 
at the bottom of the thread. 

When the section goes through the bolt in position in the 
bolt-hole, the bolt is drawn in elevation resting in the section. 
As a rule the threads are not drawn and the bolt and hole are 
represented as in Fig. 54. As the drill used for drilling the 
hole is ground at an angle of 60"^, the bottom of the hole is 



GENERAL DIRECTIONS. 



67 



■finished by the two Hnes making- an angle of 120° with each 
other. The end of the bolt is 'rounded off as a rule, the 
common radius being the diameter of the bolt. The bolt is 




Fig. 54. 

represented as screwed to the bottom of the cylindrical part of 
the hole. 

Square Threads. — The threads drawn in the figures are all 
triangular, which is the common type ; but square threads are 
used for many special purposes. The only difference is in the 
shape of the thread. The pitch and methods of finding the 
curves for the top and bottom are the same. 




Fig. 55. 

The pitch-length outside the solid metal is filled, in the 
case of the triangular threads, with a triangular-shaped figure 



68 



MECHANICAL DRA WING. 



and a space of nearly the same shape. In the case of square 
threads the portion for the metal and the space remaining are 
both rectangular. These may be equal and may differ greatly, 
as in Fig. 55. 

These threads are represented as in the case of triangular 
threads. When the drawing is large and ornamental, the 
helices are drawn ; ordinarily straight lines are used. The 
lines for the depressed portions may be left out as a rule. See 
Fig. 56. 




The pitch may be taken up by a single thread, when the- 
thread is called "single screw"; or the length of the pitch 
may be filled by two or more threads, when the thread is called 
"double screw," "triple screw," etc. 

To determine to what class a screw belongs, follow a ridge 




Fig. 57. 

around for one revolution and find how many ridges there are 
between the original point and the one arrived at after going 
around. Double, triple screws, etc., are used when a greater 



GENERAL DIRECTIONS. 



69 



longitudinal movement is desired ; in other words, when the 
pitch is increased. Then the space between the following- 
threads is filled in by extra threads for strength. 

Fig. 57 shows a single screw of great pitch. 

It is noticed that most of the bolt is cylindrical. For 
strength, there are placed between the threads two extra ones 




Fig. 58. 

that have the same pitch as the original one. Fig. 58 shows 
a triple screw as usually drawn. 

When the threads are double or triple, or when the thread 
is other than standard, it is stated on the drawing near the 
bolt. 

Hidden threads are never drawn except in the case of very 
large threads inside of nuts, as in the case of a propeller nut. 
In this case the threads are shown in broken lines, unshaded. 

When threads are drawn on bolts, it is seldom advisable 
to make the exact ending of the threads as it is in reality. 




Fig. 59. 

The tops and bottoms of threads are ended as in the sketch. 
The real ending of the top of the thread is behind the bolt 
somewhere. The bottom has to be ended according to how the 
curve or other line at the bottom cuts the teeth of the thread. 



70 



MECHANICAL DRA WING. 



Bolts and Nuts. — As most bolts are standard, the dimen- 
sions are obtained from the Table of Standard Bolts and Nuts. 
If the bolt differs from the standard, the points of difference 
are shown on the drawing. 

The diameter of the bolt is determined either by calcula- 
tions for strength or by custom. The ordinary bolts used in 
machine work have hexagonal heads ; the square-headed bolts 
are used for rough work or for special purposes. The height 
of the bolt-head and the long and short diameters are given in 
the Table. The length of the bolt is determined by the neces- 
sities of the special case. After the head of the bolt is shaped, 
the top edge is chamfered off at an angle of 45°. This is done 
by centering the bolt in a lathe and cutting the chamfer as the 
bolt revolves. This chamfer as a rule is cut just enough so 
that the sharp corners are removed, and so that the flat sides 
are left at the full height at the center. This is shown in 
Fig. 60. 




.^. 



Fig. 60. 

The point /"shows that the middle of the flat side is left at 
its full height, while at g the sharp corner is cut off. The 



GENERAL DIRECTIONS. 



71 



chamfer makes a cone of revolution which cuts the flat sides; 
the curves of intersection are hyperbolae ; but the projections 
of these hyperbolae are so nearly circles that they are drawn as 
circles. Where the cone of chamfer cuts the top plane, the 
intersection is a circle, as shown in the plan view. 

The exact representation of the top of the bolt or nut is 
shown in Fig. 61, but the 45° lines are seldom drawn in 
practice. 

From the Table of Standard Bolts and Nuts it is found 
that the height of the nut is the same as the diameter of the 
bolt, while the height of the bolt-head is less, as a rule. 











( ^ 






c ^ 




Fig. 61. Fig. 62. 

In drawing the nut, from the point a with a radius equal 
to the diameter of the bolt describe an arc, as shown. See 
Fig. 62. This is approximately the curve for the middle por- 
tion ; the continuation of this curve defines the limits of the 
long diameter of the nut. The continuation of the lines of the 
bolt defines the limits of the central face. Draw the four verti- 
cals and a horizontal line ^through e. Draw a vertical center 
line for the face be by means of small arcs from c and e, and 
find a center on this line that will cause an arc to pass through 
the points c and e and tangent to the top line. Note that, as 
usually drawn, the line across the top of the nut ends at and 
is tangent to the top of the curves for the side faces, and is 
tangent to the curve of the middle face. 

In drawing the head of the bolt (see Fig. 60), the height 
is laid off from the Table and the top line drawn. From the 



y2 MECHANICAL DRAWING. 

center of this top line lay off along the center line of the bolt 
the distance d. 

Beginning with this point, a, as in the case of the nut, find 
the centers for the side faces. 

To draw the other view of the bolt-head (Fig. 60), the 
widths of the faces are projected from the plan, and the points 
where the curves begin are projected from the other view 
drawn. These curves must have centers in the middle lines 
of the faces and must be tangent to the top line. The center 
is generally found by trial, but the length of the radius is about 
four-fifths of the diameter of the bolt. 

Although Fig. 60 shows the correct way to represent a 
bolt according to the general plan, it is customary to place the 
Side Elevation under the Plan. The reason is that the Front 
Elevation cannot be drawn until the Side Elevation is com- 
pleted, as the limits of the curves have to be determined from 
the Side Elevation. Hence it is the custom always to draw 
the Side Elevation of Fig. 60 first for any representation of a 
bolt. If two views of the bolt are made, the second one drawn 
is the Front Elevation of Fig. 60. In other words, the first 
view shows the long diameter of the bolt-head. 

In the Plan it is not good practice to draw a broken line to 
show the diameter of the bolt. 

Where a number of bolts or nuts are drawn, either in a 
straight line or in an arc of a circle, the heads always face the 
same way, whether in Plan or Elevation ; the faces of the nuts 
are drawn facing in the same way as the bolts for each view. 

I ' I I I 

!<-- -->K- -^ >K-- >1 



Fig. 63, 

Sometimes bolts are made with square shoulders under the 
head so that they will not turn when in place. The conven- 



GENERAL DIRECTIONS. 



n 



tional way of representing this square portion at any part of a 
body generally cylindrical is shown in Fig. 63. 

The portion with the crossed lines is the flat-sided portion. 

For rough work only, where the nuts are stamped out and 




Fig. 64. 

unfinished, the nuts are screwed on the bolts with the rounded 
side down, as in Fig. 64. 

Bolts that are finished always have the bottom portion 
slightly cut away at the projecting corners, so that these 
corners will not cut into the metal. 

When bolts and nuts are drawn in place, the bolt is repre- 
sented as projecting beyond the nut sHghtly. When threads 
are drawn on the bolt beyond the nut, represent the extension 





• Fig. 65. 

of the bolt as in Fig. 65. The bottom of the thread is pro- 
jected to the top of the nut on either side of the center. Aa 



74 



MECHANICAL DRAWING. 



arc is drawn through these two points, using the middle point 
of the bottom of the nut as a center. 

When threads are merely represented on the bolt, show 
the extension of the bolt as in Fig. ^6. 

The outside diameter of the bolt is projected to the top of 
the nut, and short lines are drawn and an arc drawn across with 
a radius equal to the outside diameter of the bolt. The height 
of the short lines drawn varies with the diameter of the bolt. 

Jam-nuts. — These are two nuts screwed tight together on 
a bolt, each one preventing the other from turning. These 
are generally of different thicknesses and are represented as in 
Fig. ^7. 




Fig. 67. 

The nut nearest the end of the bolt is thicker than the first 
one screwed on. Both edges of both nuts are chamfered. 

When bolts are standard, the dimensions given are 
diameter, length under head, and length of the threaded 
portion. 

When bolts are not standard, in addition to the above 
there are given the height of the head, either the long or 
short diameter of the head, and the number of threads to the 
inch. 

Tails. — When two curved surfaces meet at angles with 
rounded corners to prevent sharp angles and so that the defin- 
ing lines of one of them disappear, it is customary to represent 
this effect by short curved endings called "tails." The small 
projections represent bosses for bolts and are cylindrical. 
They gradually meet the rounded larger surface with small 



GENERAL DIRECTIONS. 75 

curves at the junction. "Tails" are placed at the ends of 
the vertical lines to represent this effect. 




Fig. 68. 

Working, Border, and Cutting Lines. — The working line 
encloses a rectangle beyond which the drawing may not 
extend, as a rule. It is laid off from the center of the paper 
both ways, using the i6 scale. The center is found by draw- 
ing with the T square diagonals from opposite corners of the 
paper (not the board). This line is pencilled but not inked. 
The idea of it is to leave a space between the drawing and the 
border line for a good effect and to avoid confusion. In 
special cases, where the scale of the drawing would have to be 
made too small on account of this line, it may be surpassed. 

The border line is ornamental only in that it gives a finish 
to the general effect of the drawing, and the blank, irregular 
spaces of the paper beyond the drawing are made less promi- 
nent. 

This line is drawn in pencil after the working line is drawn, 
and is at a certain distance outside of the working line. It is 
inked after the drawing is completed. Border lines are often 
very ornamental, and much time and care may be expended 
on them when an especially ornamental drawing is to be made ; 
but, as a rule, little time may be put upon them, as other work 
is more important. 

It is a good effect to shade the lower and right-hand border 
lines. The upper and left-hand lines are made of fair width, 
and the other lines at least four times as heavy. Plain lines 
meeting at points are sufficiently effective. Occasionally small 



76 



MECHANICAL DRAWING. 



portions of the drawing may project beyond the border Hne. 
In this case interrupt the border line for half an inch on either 
side of the outline passing beyond it. 

The cutting line is outside of the border and is drawn in 
pencil after the border line is marked. This line is simply a 
guide for cutting, and is not inked. When the line is drawn, 
it may be found that portions of the paste used in stretching 
the paper may be so far in that there will be difficulty in 
cutting off the paper finally; in this case, all the lines may be 
moved farther away from this side ; or it may be necessary to 
change the dimensions of working, border, and cutting lines, 
as is most convenient. 

In marking the working, border, and cutting lines, the half- 
distances enclosed by these lines are laid off vertically and 
horizontally along center lines drawn in these directions 
through the center of the paper. These distances are marked 
once only. The T square and triangles are depended upon 
for accurate lines. 




«<x, Cutting fines 
66, border .. 
cc, working; >> 



Fig. 69. 

Legend, Lettering, Scale, etc. — The legend refers to the 
description of the drawing, with the scale and the name of the 



GENERAL DIRECTIONS. 'J'J 

one who made the drawing. All these records are placed in 
the lower right-hand (S. E.) corner of the drawing inside the 
working edge, and space must be left for them when calculat- 
ing on the best arrangement of the different views. This 
generally leaves a blank space along the upper right-hand edge 
of the paper, but the effect of the drawing as a work of art is 
sacrificed to utility. As drawings are stored in drawers and it 
must be possible rapidly to find the one sought, the descrip- 
tions must be in the same place in all, and they must be at 
one of the lower corners, so that it may be possible to read 
them without pulling out each sheet. By raising the right- 
hand corners of a number of drawings, the legends may be 
rapidly looked at and the one desired found with the least loss 
of time. 

In the S. E. corner is placed the general description of the 
drawing or drawings on the board. If a number of objects are 
shown, find as generic a name as possible for them all, but one 
that will leave no uncertainty as to what may be on the draw- 
ing. Besides the very general description in the S. E. corner, 
place near (under, if convenient) each different drawing any 
especial remarks that may be necessary to more thoroughly 
describe it. 

When drawings are made from brass models, after the 
name of the object the legend reads : ' ' Sketched and drawn 
from models. " 

When drawings are made from portions of machinery, after 
the name of the object the legend reads : ' ' Sketched and 
drawn from work." 

When drawings are made from blue-prints of general 
arrangements, first give the name of the ship (Battleship Iowa, 
Cruiser Detroit, U. S. S. Adams, etc.), then the description 
of the object or objects; after that the legend reads: " Taken 
from blue-print of General Arrangement of Machinery. " 

If all the drawings on the sheet are taken from the same 
work, the legend in the S. E. corner may contain the re- 



78 



MECHANICAL DRAWING. 



in 



<A 



U 



— LG 



CL 



U 
DC 

ID 

cn 

CD 

X u 

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Q_ 

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NO 












55 







GENERAL DIRECTIONS. 79 

marks showing whence the material for the drawing came; in 
case the drawings are from different sources, the special re- 
marks are placed near the different drawings. 

In the legend, the sequence of the different portions is as 
follows : 

Name of object represented. 
Special remarks. 

Scale. 

Name. Class. 

Date. 

The name of the object is made in some type of heavy 
lettering and is the prominent part of the legend. When a 
ship's name or number is given, this is equally prominent. All 
the rest of the lettering is done with a writing-pen, the letters 
small and clear. The name is not prominent and is an 
autograph. 

Block Letters. — This is the type of lettering preferred for 
heavy type. The letters, as a rule, are three spaces wide and 
all are five spaces high, as shown in the sketch, while one 
space separates the letters. The letters M and W occupy re- 
spectively four and five spaces, as shown. The peculiarity of 
the letter K is shown. The peculiarities of the figures are also 
shown. 

Numerous variations of these letters may be made by vary- 
ing the heights, widths, slopes, etc., of the spaces; by making 
solid or skeleton letters ; by drawing shade lines ; by drawing 
the shade lines only; by shading in any direction and to any 
extent, etc. 

Sample drawings of these letters are found in the drawing- 
room. 

When block lettering is to be used, measure the length of 
space that is available and draw a vertical center line. Make 
a rough copy of the letters to go on one line on a spare piece 
of paper. Allow the spaces between the words and place 



So 



MECHANICAL DRA WING. 




GENERAL DIRECTIONS. 



8i 




82 



ME CHA NIC A L DRA WING. 



figures over each letter and the following space for the number 
of the spaces actually needed. Half the sum of these figures 
gives the part of the lettering to coincide with the center line 
drawn. From the half-width of the space available and the 
half-number of spaces required, the width of one space is cal- 
culated. The next smaller division on a regular scale may be 
used and the spaces laid off from the triangular scale ; or the 
exact width desired may be obtained very closely and this dis- 
tance laid off with the bow spacers on a line just below the 
one for the bottom of the letters. The vertical lines for the 
spaces may then be drawn and the height chosen for the ver- 
tical spaces. For ordinary work letters need not be over half 
an inch high, and three-eighths of an inch is amply large for 
most drawings. 




Another type of block letters is shown. In this case, 
decide on the total width allowable for each letter and its fol- 
lowing space, and lay off these total spaces; then decide on 
how much of these total spaces shall be letter and how much 
distances between letters. Divide the laid-off spaces accord- 
ingly. Draw horizontal lines for determining the beginnings 
of the slopes at any desired distances from the top, middle. 



GENERAL DIRECTIONS. 83 

and bottom lines. Where these Hnes cut the vertical bounding 
lines of the letters the angular lines begin. The slopes may 
be varied, the slopes made arcs, and the slant of the lines 
may be changed as desired, but for ordinary drawings the 
simple type is best. These letters are generally drawn with 
an opening of the pen that will ensure a good line that may 
be continued indefinitely and that is at the same time quite 
heavy. 

Free-hand Lettering. — There are many types of free-hand 
lettering, but the simplest and most clear and the easiest made 
are the best. No time should be wasted on the lettering, but 
it must be distinct. The samples given are very satisfactory 
and are much used. A little practice brings a fair proficiency. 
It is well to draw the top and bottom guide-lines for the capi- 
tals as well as the small letters. 

The height of the small letters is about y^" , and of the 
capitals '^/ J' . 

The figures are the same height as the capitals. 

Variation may be made in the slope of the letters and indi- 
vidual designs used to a certain extent, but the simpler and 
more upright the letter the better. 

Use an ordinary writing-pen. Try many kinds until the 
most satisfactory result is obtained. Always make the letters 
and figures distinct. 

After the drawings of brass models are completed, the 
different views are no longer marked " Plan," " Front Eleva- 
tion," etc., as it is supposed that all are familiar with the dif- 
ferent views by that time. 

Scales. — The scale of the drawing is clearly stated. If 
only one scale is used throughout the drawing, this scale is 
given in the legend. If different scales are used in different 
parts of the drawing, the various scales are placed near the 
drawings where used, generally under them, so that there may 
be no possibility of error. 



84 MECHANICAL DRAWING. 

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GENERAL DIRECTIONS. 85 

Scales are stated as follows: Scale, 3" — i foot; y^" = i 
foot; etc. 

Scales other than those on the triangular scale are stated : 
Scale, full size; scale, half size; scale, three-quarter size; 
scale, double size. 

Never state: Scale, ?<( size. Always write out the frac- 
tion. 

Never state: Scale, 9" = i foot; or. Scale, 8" = i foot; 
as there are no such scales on the triangular scales used. 

Line Shading and Tinting. — Line shading and tinting are 
used for ornamental drawings, and to show more clearly to 
those not familiar with mechanical drawing the intention of 
the views and the arrangement of the different parts of the 
mechanism. 

As shown by the title, the surfaces are covered with lines 
or tints of different light effects to show as clearly as possible 
how the object really appears. 

Line Shading. — There are certain prevailing methods of 
shading surfaces, and these methods apply to all views of an 
object. 

The light is supposed to come from the same point as 
under "Shade Lines," that is, from the N. W. direction and 
from an angle of 45° above the drawing-board. 

Flat Surfaces. — Fig. 70 shows two positions of half of a 
hexagonal prism with a smaller hexagonal prism cut out 
centrally. These views give some of the various types offlat 
surfaces to be considered. 

Flat surfaces parallel to the paper and on which the light 
falls have a uniform light effect, as surfaces A. 

Flat surfaces parallel to the paper and on which the light 
does not fall have a uniform dark effect. 

Flat surfaces on which the light falls and which are inclined 
to the paper have a light effect which gradually becomes darker 
as the surface recedes, as surfaces B. 



86 



ME CHA NIC A L DEA WING . 



Flat surfaces on which the h'ght does not fall and which 
are inclined to the paper have a dark effect that gradually 
becomes lighter as the surface recedes, as surfaces C. 

Generally speaking, striking contrasts are made at the front 
of the drawing: the parts near the eye are in high light and 





Fig. 70. 

deep shades, while those parts in the background have less 
contrast as they are farther away, the parts in the light being 
less bright, and those in the shade less dark. 

To Shade a Cylinder. — In order to produce the rounded 
effect of the cylinder, lines or tints are graded from light 
effect to darker ones. The heaviest part of the shade is theo- 
retically at the position of 45°, as shown in Fig. 71. The 
point of lightest effect is theoretically at a position of 22^°, as 
shown. 

It is not deemed necessary to study the reason for these 
points of light and shade. After these points are determined, 
it is in accordance with the best practice to move these posi- 
tions somewhat in order to produce a better effect. The 
darkest part is moved nearer to the central line of the figure, 
and the lightest part is moved farther away from this center. 



GENERAL DIRECTIONS. 



87 



The amount of this movement is proportional entirely, and 
Fig. 71 gives about the right amount. After finally establishing 
the dark and light lines, one method of line shading is shown 
in the above figure. In this case all the lines are of the same 
breadth, and the effect of rounding is produced entirely by 
varying the distances apart of the lines. A clear line, com- 




FiG. 71. 

paratively fine, is chosen and the lines are drawn in succession 
from one side to the other, the gradations of space being made 
according to judgment. It seems best to begin at the side of 
the cylinder nearest to the lightest line, and to follow along 
to the other. The effect at the edges should be exactly the 
same. 

Fig. 72 shows the more ornamental and effective kind of 
line shading. This is more extensively used also. The dark 
and light portions are established as before, and the rounding 
effect is produced by a combination of varying the width of 
the lines and also the distances apart. Often three or four 
of the darkest lines at the darkest point of the shading are 
combined in one. It seems best to begin this shading on the 
left side — that nearest to the lighter portion. The line first 
drawn should be well chosen and in accordance with the size 
of the cylinder. This line will establish the weights of the 
other lines and practically whether the cylinder will be shaded 
dark or light. After the first line, the others are varied 



88 



MECHANICAL DRAWING. 



according to judgment. At times three or four lines of the 
same width are drawn, the spaces between them slightly 
varied. The combination of varying the width of the lines and 
the width of the spaces gives a good chance to round the 





Fig. 72. 

cylinder up nicely. At the end, note that there is always a 
light effect near the edge last finished. There is a slightly 
wider space left between the last two lines and the others just 
drawn. This produces the effect of a light streak just near the 
edge. This is supposed to be the effect of reflected or diffused 
light coming around the side of the cylinder. 

This effect is never shown at the other side of the cylinder ; 
the shading there is gradual to the very edge. 



GENERAL DIRECTIONS. 



89 



Interior of a Hollow Cylinder. — As shown in Fig. 73, the 
heavy part of the shading commences at the edge in shadow 



Fig. 73. 

and grades to the lightest part, found as before; then the 
shading continues to the other side gradually. 




A Cone. — The dark and light points are established as in 
the case of the cylinder and the same system is followed. In 
the heavy type of shading each of the shade lines becomes a 
triangle. The light effect at the side nearest to the heavy 



90 



MECHANICAL DRAWING. 




Fig. 74- 

shade lines is preserved as in the case of the cylinder. It is 
found advisable in shading the cone to draw the lines from the 




Fig. 75. 



GENERAL DIRECTIONS. 



91 



apex and to begin at the heaviest shading, working both ways. 
Many Hnes are not begun at the apex but a Httle below, to 
avoid a blot. When all the lines are drawn, the light spaces 
near the apex are filled in with a fine opening of pen. 

A SpJiere. — The darkest and lightest points are on the 
45° line as shown, and their approximate radial positions 
determined by eye. See Fig. 75. 

These lines are drawn as shown under "Shade Lines." 
A horn center should be used. 




Fig. 76. 



92 MECHANICAL DRAWING. 

Another method. (Fig. 'j6.') This does not produce the 
true effect, as the varying Hghts traverse the surface in zones, 
but it is much easier to make and is much used. The center 
of the arcs is the center of the lightest portion. 

Tinting. — The same methods of arranging the lights and 
shadows of the shading apply to the tinting. 

Tinting may be done with any colors or with Indian ink. 
Colors are seldom used ; and as the same methods apply, the 
description of the method of using Indian ink will answer. 
Use stick Indian ink — not the ink mixed in bottles. 

The paper must be stretched on the board if tinting is to 
be done. The drawing must be kept as clean as possible, and 
the rubber not used, as it roughens the surface of the paper. 
The tinting is done after the black lines of the drawing are 
completed without shade lines. The drawing is then washed 
in running water — not rubbed — and is allowed to dry. 

To Prepare the Tint. — At least tv/o brushes are needed; 
two beakers or water-glasses partly filled with clean water; an 
ink-slab or saucer in which to mix the ink; a stick of Indian 
ink; and a piece of blotting-paper. 

Clean all these articles thoroughly. Decide on the amount 
of liquid ink necessary according to the quantity of surface to 
be covered. Place sufficient water in the ink-saucer and pro- 
ceed to grind the ink in the water by rubbing it about with a 
certain pressure on the bottom of the saucer. This requires 
considerable time, as the ink dissolves slowly. It should be 
ground until a line made with it by the R. L. pen remains 
black when dry. This ink is now in condition to be used for 
drawing. As the ink used in tinting is very much lighter in 
color, the ink mixed will serve to cover from three to four times 
the surface that it would cover if used in its black state. In 
one of the water-glasses or beakers place a small quantity of 
water ; dip the brush in the top of the mixed ink, so as to take 
up only the clear ink and leave the sediment, and stir this color 



GENERAL DIRECTIONS. 93 

into the water in the beaker. With a brush test the color of 
the tint on a piece of drawing-paper, allowing the color to dry. 
Add black ink until the tint is as desired. The tint chosen 
should be much lighter than will be the final effect on the 
drawing, as it is very easy to darken the drawing by laying on 
another tint, while it is very difficult to repair work that is too 
dark. 

Take a clean brush and clean water and carefully go over 
the surface to be tinted with this water; be particularly careful 
that the edges are moist to the boundary lines and that these 
are not passed, as the tint will follow all these defects. 

To Lay on a Flat Tmt. — This seems easy but is extremely 
difficult, and methods differ also. Some leave the drawing- 
board level and others tip it slightly, so that the bottom of the 
board is three inches or more lower than the top. Draftsmen 
follow the methods that suit them best. The same general 
plan is followed in either case, only that it is thought that when 
the board is tipped the tint flows by gravity and assists the 
operation. However, as it is difficult to tip the board in all 
the directions required in making a complicated drawing, it is 
well to learn to tint with the board horizontal. 

After a space has been moistened slightly with the clean 
water, dip a brush deeply into the prepared tint and stir it well 
around so that it is permeated with the same shade of color; 
either keep the brush full for a large surface, or for a small one 
remove part of the liquid by rubbing the brush on the edge of 
the glass; according to the shape of the surface, carry the 
brush along one line rapidly and carefully; before this has a 
chance to dry, run the brush again along in the same direction 
but a little farther on from the edge, thus making the surface 
moistened twice as wide as before ; continue in this way, never 
allowing an edge to dry until the whole surface has been 
covered ; at the end, if there is too much of the tint on the 
paper, quickly dry the^ brush by rubbing it on a piece of 
blotting-paper and then use it to dry up the last part of the 



94 MECHANICAL DRAWING. 

work. If carefully done, it will be found that a perfectly even 
coat of color has been placed on the surface. If this tint is not 
dark enough, it may be darkened by successive tintings ; but 
never put on a second tint until the first one is "hand dry," 
or dry to the touch. Never try to touch up a small portion of 
the surface except by " stippling, " which alters the entire effect 
of the work. 

When using the brush along the boundary lines of the 
space, always keep the point of the brush towards the edge., 
Do not bear on the brush, as this may cause marks to be made 
that will show under the tint. 

For large surfaces lay on a light tint. Reverse the board 
and lay on a second one. Turn the board and repeat from 
one side; then do the same from the other side. This does 
away with the effects of streaks in any one direction, and the 
result is an even tint over the whole surface. 

Graduated Tints. — There are two general methods, the 
French and the American. 

The French method consists in dividing up the space to 
be covered into small rectangles (these must not be marked 
with pencil, as the marks cannot be eradicated) ; putting on a 
tint in the rectangle to be darkest and allowing it to dry; 
putting on a tint covering the rectangle already tinted and an 
adjacent one and allowing it to dry again ; and continuing this 
operation until the entire surface is covered. By this method 
the shading is in streaks that are more or less prominent 
according to the width or narrowness of the rectangles. This 
method takes too much time also. 

The American method is most used and takes less time, 
while the effect is equally good. This is called the method of 
shading by softened tints. For a surface that is flat and 
inclined at an angle to the paper, the method is as follows : 

Saturate the brush as before with the tint and remove most 
of it against the side of the beaker; lay a narrow line of the 
tint along the line of darkest shade; while this is still wet dip 



GENERAL DIRECTIONS. 



95 





Fig. 77. 



Fig. 78. 




Fig. 79. 



Fig. 80. 



96 



MECHANICAL DRA WING. 




_^ 




Fig. Si. 




Fig. 82. 



GENERAL DIRECTIONS. 97 

the point of the brush in clean water, which dilutes the color 
on the brush, and apply a line along the edge of the tint 
previously laid on, rubbing into the edge of the other tint; 
again weaken the tint and continue as before. Each operation 
leaves a lighter tint, and at the end a clean brush in clear water 
leaves practically no color. This method softens the grada- 
tions from one tint to another and is rapidly iinished. 

When the surface is dry the operation may be repeated and 
thus continued until the desired effect is produced. 

For large surfaces it is well to mix three or more tints of 
varying darkness. After laying on the first line of the darkest 
tint, dip the brush in the next darkest and so carry on the 
shading until approaching the light edge, when finish with a 
clean brush and clear water. 

In shading cylinders, cones, and spheres, the work is done 
very rapidly, as the dark tint is first laid in the interior of the 
surface and the shading must be carried away from the edges 
of this first tint in all directions before any of it may become 
dry. 

Stippling. — When the work is uneven, as is often the case, 
due to irregularities in the paper and lack of experience, 
stippling may be resorted to to improve the effect. Fill the 
brush with a light tint and remove most of the color; touch 
the lighter portions of the tinting with the point of the brush 
until the surface is brought to the right effect by these points 
of color. After stippling, it is well to go over the whole sur- 
face with an even light tint to smooth down the effect. Many 
draftsmen stipple a drawing after the shading is complete, as 
it is thought to improve the effect. 

Tracing. — If more than one copy of a drawing is required, 
it is traced, and blue-prints are made from the tracing. The 
business method is to make the original drawing in pencil only ; 
this is traced in ink, and the tracing is kept as the original. 
The pencilled drawing is not retained. 

Tracing-cloth or paper is transparent; it is tacked in place 



98 MECHANICAL DRAWING. 

over the drawing as described under " Thumb-tacks," and the 
method of tracing follows the method of inking the original 
drawing as described under "Plan of Procedure. " 

Tracings are made on the smooth or shiny side of the 
paper. As there is sometimes trouble in getting the ink to 
run freely on the tracing-cloth, special powders are furnished ; 
dust on a little powder and rub it around with a cloth. 
Electro-silicon is found to be an excellent powder for this pur- 
pose. A blackboard-eraser saturated with chalk is sometimes 
rubbed gently across the paper for the same purpose and 
answers as well. 

The tracing is completed, lettering, border lines, legend, 
etc. It is then removed from the board and trimmed, and blue- 
prints are made. 

Be careful not to wet the tracing. 

Errors should be erased only with the rubber ink-eraser. 
After that, rub the surface with a soapstone pencil and polish, 
with agate or other hard substance. 

Blue-printing. — The tracing is placed in the printing- 
frame, the shiny or drawing side next the glass ; the sensitive 
paper is placed next the tracing, the sensitive side towards the 
tracing; the backing is put in place and the frame placed so 
that the sun's rays strike normally. Ordinarily in from five to 
ten minutes the print is completed. The print is removed from 
the frame in as dark a place as is convenient, and is then placed 
face down in a bath containing clear, running water sufficiently 
deep to cover the paper well. 

The print is moved about occasionally and remains in the 
water about fifteen minutes. The action is made more rapid 
by placing a small quantity of ordinary salt in the water. 

The print is now dried, preferably by being tacked at the 
upper edge so as to hang vertically. In this way it does not 
become curled and troublesome. 

These blue-prints are now the working drawings used, as 



GENERAL DIRECTIONS. 99 

many copies may be furnished ; the original, the tracing, is 
carefully preserved. 

Line shading may be very well done on tracing-cloth, but 
the tinting draws the cloth out of shape as the tint dries. So, 
instead of tinting, colored chalk is rubbed on the back of the 
tracing. 

The same light and dark effects may be produced as with 
tinting, and the blue-print carefully reproduces these effects. 

To write on a blue-print (white characters), or to scratch 
•out or wipe out any portion that has been printed, use a 
saturated solution of sal-soda (washing-soda). 

If the blue print is underexposed, it may be developed by 
acetic or hydrochloric acid bath. 

The ordinary blue-print consists of white lines on a blue 
ground. Many prefer blue or black lines on a white ground. 
This is accomplished by printing from the tracing on special 
paper a "negative " which consists of white lines on a black 
ground. By using this '* negative " instead of the tracing, a 
print of either blue or black lines on a white ground may be 
produced. 

Sketches. — Sketches are considered one of the most impor- 
tant parts of the course. They are made in the sketch-books, 
free-hand, not to scale. The attempt is made to sketch as 
well as possible an accurate representation of an object in the 
different views needed, and to preserve quite accurately the 
relative proportions of the object. Dimensions are carefully 
taken with calipers and rule only and are clearly marked on 
the sketches. 

The idea to bear in mind when making sketches is that 
there will be no further opportunity to see the object after once 
the sketch is completed ; it is supposed that the one making 
the sketch is on detached duty and must make a sketch so 
accurate that he will be able to make a working drawing of the 
object at any later date. 

No instruments whatever are used in making the sketches. 



L.ofC. 



lOO MECHANICAL DRA WING. 

The pencil used is softer than HHHHHH and is sharpened to 
a point, and should be kept fairly sharp if good work is 
attempted. 

The first sketches are made on the lined paper in the front 
part of the sketch-book. This assists in learning how to make 
straight lines free-hand, and also assists in drawing lines per- 
pendicular to each other and in preserving the general propor- 
tions of the sketches. After the drawing of the brass models 
is completed, sketches are made on the unlined paper in the 
other parts of the book, as it is considered that all may have 
acquired sufficient ability by that time, and the lined paper 
may not always be at hand. 

The sizes of the sketches are not in proportion to the size 
of the object sketched, but are large enough so that all details 
may be shown without confusion and so that all dimensions 
may be readily placed and clearly read. 

As a rule, the same views are made in sketching as are made 
on the drawing-board, and the same dimensions that are placed 
on the sketch are eventually placed on the drawing. In the 
sketch, however, there are many abbreviations and lessenings 
of work. It is sufficient to represent a portion of the work. 
If a large surface is to be hatched, in the sketch only a small 
portion need be hatched, as it is understood that the remainder 
must be treated in the same manner. If there are a number 
of threads or bolt-holes of the same kind, it is sufficient to 
sketch one of them carefully and indicate the number and 
positions of the others. 

The first thing to do when beginning a sketch is to ex- 
amine the object and decide what sketches are required and 
then decide in what order to make them. If the book is suffi- 
ciently large, the general plan is followed and the points are 
projected from one drawing to the other. The projecting lines 
are not drawn. There may be a choice as to which one is 
drawn first. It may be the Plan, the Side Elevation, or the 
Front Elevation, but it is best to draw first the one that gives 



GENERAL DIRECTIONS. 10 1 

the best general idea of the object and the most points to 
project from. 

After the views are decided upon, next draw the center 
lines. Then the sketch continues according to the ideas of the 
sketcher. 

The sketches are made quickly, a free sweep of the hand 
for the lines and a rapid proportioning by eye of the parts. 
After the sketches are completed, the arrow-points are placed 
on the sketches for the ends of the dimension lines. Cover the 
sketches with these arrows, deciding quickly what dimensions 
are needed. Then draw rapidly the dimension lines, leaving 
the spaces for the dimensions. Then make the measurements 
quickly and accurately and place them on the sketch. In this 
way the work goes on systematically and quickly. After 
completing the sketch, go over it with the idea of noting 
whether the object could be constructed from the notes taken 
and the sketch made. Write on the sketch the kinds of metals 
used in the different parts, unless these are shown by the 
symbolic hatching. Note if any of the bolts or nuts differ 
from the standard. Note what parts of the object are finished, 
and so state on the sketch. If the object is finished all over, 
note on the sketch, " Finished all over." 

If a complicated machine is to be sketched, first make a 
free-hand sketch of the general outline, omitting all lesser 
details, but take special care to get the exact positions of the 
principal centers in all views. After the general view is 
sketched, the details may be drawn one by one. 

The sketches must not be overcrowded with details. 

From the dimensioned sketches the scale drawings are 
made. The scale of the drawing is decided upon, bearing in 
mind a correct and neat arrangement of the required views and 
the space for the legend. 

Fig. 83 is a sample of sketching when the lined paper is 
used. It is seen that two views, part of one in section, are all 



I02 



MECHANICAL DRAWING. 



that are needed for a thorough representation of the object. 
The section shows the material to be cast iron. 



















































































































































































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Fig. 83. 



Plan of Procedure in Making a Drawing. — After the 
paper is stretched or tacked on the board and is ready for use, 
the following is the sequence of the different operations in 
making the drawing and blue-print (if required). 

1. Examine the object to be drawn, and decide what views 
are necessary so that it may be properly represented. 

2. Make dimensioned sketches. 
Center the drawing-paper. 

Mark the working, border, and cutting lines in pencil. 
Decide on the scale to be used. 
Establish the positions of the center lines and pencil 



3- 
4- 
5- 
6. 



them in carefully. (Special directions are given for the first 



GENERAL DIRECTIONS. \0% 

drawings or sheets, so that from this point the methods may 
vary sHghtly; but the same general plan is followed.) 

7. Inspection of the drawing. 

8. Pencil the drawing. 

9. Inspection. 

10. Ink the drawing in black ink: no sections, no tinting, 
no shade lines. 

1 1. Inspection. 

12. Tint or line shade, if required. 

13. Inspection. 

14. Draw center lines in red ink. 

15. Draw extension and dimension lines in red ink. 

16. Make the dimension figures and arrows in black ink. 

17. Inspection. 

18. Hatch sections. 

19. Inspection. 

20. Draw shade lines. 

21. Inspection. 

22. Make the legends and other lettering in black ink. 

23. Draw the border lines in black ink. 

24. Clean the paper. 

25. Inspection. 

26. Trace drawing. (If required.) 

27. Inspection of tracing. 

28. Remove and trim tracing, and cut the drawing from the 
board. 

29. Make blue-prints. 

30. Stretch paper for the next drawing. 

Remarks on the above: Before beginning any operation, 
read the remarks under that head. 

Pencilling the Drawings. — Read carefully the remarks 
under " Pencils." 

Note carefully the remarks under "Center Lines" and 
carefully make all measurements from them as far as possible. 

Lay off first all center lines for portions of drawings. 



I04 MECHANICAL DRA WING. 

When straight lines are joined by arcs in pencil-work, the 
straight lines are generally drawn first and centers of the arcs 
found and the arcs drawn so as to be tangent to the lines. 
The methods given in Geometry generally cover all cases. 

When inking, the reverse method is followed, as the centers 
are already found ; these centers should be made distinct in the 
pencilling, so that they may be readily found when inking. 

Make no shade lines in pencil-work. 

Do no hatching in pencil-work. 

When a large number of lines radiate from a point, draw 
the outer lines to the point and stop all the others at a distance 
of from y^" to -y" away. 

Leave no centers to be found when inking, and leave no 
lines to be "faired." The pencil-work must be complete 
except for shade lines, hatching, dimensions, and tinting. 

Plan of Procedure in Inking.— Ink all the arcs on the 
board first, beginning with the largest; then ink all the irreg- 
ular curve lines; then the straight lines. Always draw the 
straight Ywi^s frovi the curves if possible — never towards them. 

After finishing the arcs and irregular curves, use the tri- 
angles, beginning at the top of the board. Place the T square 
so that the triangle laid in place will reach just above the 
highest lines on the board. Beginning at the left sweep across 
the board with the triangle and draw the vertical lines found 
at any part of any one of the drawings or views. Then lower 
the T square and again sweep across with the triangle ; and so 
on until all the vertical lines on the board are completed. 

The horizontal lines are drawn by means of the T square, 
beginning at the top of the board and sweeping the T square 
from top to bottom, drawing lines as they appear above the 
T square at any part of the board. 

Read carefully the remarks under " R. L. Pen." 

If the drawing is to be tinted or covered with line shading, 
note carefully the remarks under these headings, and take care 
not to draw a heavy line until the drawing has been washed. 



GENERAL DIRECTIONS. 10$ 

In shading the circles, follow the method as in drawing 
them; shade the large ones first, then the smaller ones, etc. 

Read carefully the remarks under " Shade Lines." 

General Remarks. — Note always and continually the direc- 
tion from which the light should come. 

Keep the instruments clean. Clean them at once when 
through using them. 

Keep the instruments not in use off the drawing-board. 

Keep the paper clean. 

Come to the drawing-room with clean hands, and clean 
them often while drawing, if necessary. 

Cover the portions of the drawing not being worked upon 
with paper or cloth to keep them clean and the lines clear. 

Never do free-hand work that may be done with the instru- 
ments. Even " breaks " and " tails " may be made best with 
instruments. 

The excellence of the work is of far more importance than 
speed. It is better to make one good drawing than a dozen 
poor ones. Speed combined with excellent work is the object 
aimed at, but the speed must come last. 

Pens that are dull, or instruments requiring repairs, may be 
turned in to the desk. It is advisable, however, for all to learn 
to sharpen their own pens. 

When compass pens require sharpening, turn in the whole 
instrument, so the sharpening may be tested. 

Pens that are found to be soft may be turned in for retem- 
pering. 

Attach to the instruments turned in a slip of paper giving 
name, class, and repairs needed. 

Write the names clearly on the covering cloths and on all 
triangular scales, irregular curves, etc. 

Write the names clearly in ink on the N. W. corner of the 
drawing-paper outside the border line. 

Bring all models to the middle of the room at the end of 
the period. 



FIRST DRAWINGS. 



These consist of three sheets. Sheets I and II are for the 
purpose of teaching the use of the instruments ; Sheet III is a 
study of Projection and Working Drawings. In Sheets I and 
II there are eighteen figures. Each figure represents a block 
raised above the drawing-board. Some of the figures show 
lines drawn on the upper surface of the blocks, and some show 
other figures resting on the top of the original one. The 
figures in these two sheets are all ' ' Plans. ' ' The remaining 
portion of the sheets is for the "Legend." Every scale on 
the triangular scale is used in each of these sheets. 

Sheet I consists of straight lines only. The attempt is 
made to bring into this sheet all kinds of straight-line work. 

Sheet II consists of arcs ; combinations of arcs and straight 
lines ; combinations of arcs with other arcs and with irregular 
curves ; irregular curves. The attempt is made to bring into 
this sheet all kinds of curved-line work. 



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--34'—- 



General View of Sheets I and II. 



io6 



FIRST DRA WINGS. \Q'J 

Sheet III consists of drawings of brass models. Three 
views are made of each model and the points are all projected. 
The models are cut across in certain planes and are pinned 
together. They may be separated at the planes, and sections 
studied and drawn. They are then hatched with Standard 
Hatching. 

The figure on p. io6 shows the dimensions of the Working, 
Border, and Cutting Lines used in all drawings. It also gives 
the dimensions of the figures in Sheets I and II. 



SHEET I. 

As stated under "Working, Border, and Cutting Lines," 
center the drawing-paper and draw the lines. Measure once 
only for these lines and carry the lines across from these 
measurements. The T square and triangles are depended upon 
for the rectitude of the lines. 

On the first ruled page of the sketch-book make a sketch 
of the general view of the sheet, placing there the dimensions 
of the bounding lines of the paper and of the figures of the 
sheet. Full directions should be given with the sketch so that 
the outlines may be drawn from it. This should occupy only 
about one-fourth of a page in the sketch-book, leaving room 
for some of the figures. 

Mark off to " full-size scale " the boundaries of the different 
figures of the sheet. Measure along the center lines and draw 
carefully. One measurement only should be made for each 
line, and the lines should be carried across the board. 

The outer lines of the figures coincide with the working 
lines of the paper. 

Sketch each figure in the sketch-book before putting it on 
the drawing-board. The text-book is kept closed and the 
work is done entirely from the sketch-book. The text-book 
is to be used only for correcting the sketch. 

Pencil-work. — Place Fig. i in the upper left-hand corner; 



I08 MECHANICAL DRAWING. 

continue on to the right along the upper row of figures ; begin 
again at the left hand of the second row and continue as before 
to the right; leave the legend until all the figures are inked. 

Finish completely all the figures in pencil before inking any 
figure. 

When a line of figures is completed cover it with paper. 

Pencil-lines cannot be made too fine, provided they are 
clear-cut and distinct. See notes under ' ' Pencils and Pencil- 
ling. ' ' 

When the pencil-work of all the figures of the drawing is 
completed, the drawing must be inspected before the next step 
is begun. 

Put no dimensions in pencil on the drawing. 

Ink-work. — In inking, do not make too fine hnes. Follow 
the directions under "Use of the R. L. Pen." 

For this sheet disregard the general instructions for inking 
drawings, and ink each figure in fine lines in its order as 
pencilled, but ink none until all the pencil-work is completed. 

When inking the drawing, make all the lines of the same 
figure and of the same type of the same width. Set the pen 
before drawing the first line, and draw a sample line on the 
margin of the paper beyond the cutting line, taking care to 
draw this line by guiding the pen against the T square or tri- 
angle. Often test the pen by drawing a line near the sample 
line for comparison. 

When all the figures are inked, the drawing must be 
inspected before the next step is begun. 

After the first black lines are inspected, the center lines, 
dimension lines, dimension projection lines, arrows, and figures 
are completed according to the directions given under the proper 
headings. The red-ink lines are made as fine as possible. 

Another inspection of the drawing follows. 

After the red-ink work is inspected, draw the shade or 
relief lines on the right-hand and lower sides of the figures and 
on the other parts as required. Make these lines about four 



FIRST DRA WINGS. 



109 



times as heavy as the other parts of the drawing. These lines 
are drawn over the Unes previously drawn, but the extra width 
of line is outside of the original lines. All these shade lines 
are of the same width throughout the sheet, and they must not 
be too heavy. The pen is opened the right amount, and the 
line made with one sweep. 

In drawing these shade lines, draw the vertical ones first. 

Another inspection of the drawing is made after the shade 
lines are completed. 

After the shade lines are inspected, the legend is placed in 
the space reserved for it. Lines are drawn in pencil at the 
proper distances apart and the block letters are laid off. Care 
must be taken to calculate the spaces occupied by the letters 
so as to have the letters central in the space left for the pur- 
pose. See notes under "Lettering." 

The lettering of the free-hand type is next made, the name 
written, and then an inspection follows. Scales are marked 
as stated under " Triangular Scale." 

After this inspection, the border lines are drawn and the 
drawing cleaned. 

A final inspection follows, and then the drawing is cut from 
the board. Paper is stretched for the next drawing. 



TT 

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Sheet L Fig. 1. 

Scale, full size. (Use i6 scale.) 

Horizontal full lines. 



no 



MECHANICAL DRAWING. 



T square ; triangular scale ; full lines, pencil and ink. 

Pencil-ivork. — Measure off the vertical distances as given 
and mark the points with the bow spacer or compass-points. 
Draw lines across at all marked points. 

Sweep the lines across in pencil from left to right, not at- 
tempting to begin or stop the lines exactly at the boundary lines. 

bik-work. — The lines are full lines of equal width. Each 
line must be clear, the nibs of the pen cutting sharply. The 
endeavor is to make the lines exactly alike, equal in width and 
distinctness. Begin the lines firmly, and carry them on with 
an even pressure, and stop them exactly at the boundary line. 

Do not draw the dimension lines until all the figures are 
completed. See notes under "Dimension Lines." 






V'H . >I'K >|'k 



1111 



I I I I jllll 



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~*1< X ^* 8 1* 8*^ 

Sheet I. Fig. 2. 

Scale, full size. (Use i6 scale.) 

Vertical broken lines. 

T square; triangular scale; triangles; full lines in pencil, 
broken lines in ink. 

Fig. 2 is the same as Fig. i turned through 90°. 

The pencilling is done as before, full lines drawn from 



FIRST DRA WINGS. 



Ill 



bottom to top and using either triangle, sliding it along the 
T square and noting that the lines are drawn from bottom to 
top and on the left side of the triangle. 

When inked, the lines are drawn as broken lines. 

The lengths of the dashes and spaces are estimated by eye, 
not measured. 

The lines to the left are made with dashes about yi" long, 
and the spaces are about yi" wide. The dashes and spaces of 
successive lines break joints with each other irregularly. 

The next lines to the right are made with dashes about 
){" long, and the spaces are about ^g" wide. 

The next lines to the right are made with dashes about 
yi" long, and the spaces are about i^" wide. 

The next lines to the right are made with dashes about 
Jg" long, and the spaces are about gV' wide. 

In drawing these lines the endeavor is to make the lengths 
of lines and widths of spaces of each set of lines as uniform as 
possible, and to make each line exactly as wide and as promi- 
nent as the others. 
































































Sheet I. Fig. 3. 

Scale, 3" = I foot, or one-fourth size. 

Horizontal heavy lines. 



112 MECHANICAL DRAWING. 

T square; triangular scale; full lines of varying widths 
when inked. 

Pencil-work. — From one of the top corners measure down- 
ward the following distances, each distance measured from the 
corner: yi" ', s/^" ; Y^" ', i%" ; i%" ', 2S/^-- 3^-; 41^-; 
SVi"\ 6^"; ^}i"; 9%"', ^^}i"- The remaining distance is 
ys", which is a check. 

Draw a vertical center line and horizontal lines through 
each of the points marked. 

Ink-work. — Draw the boundary lines and the lines through 
the marked points. These lines are fine lines. Shade the 
right halves of the lines as in the figure. The top line is the 
fine line already drawn. Make each line in succession heavier 
than the preceding line. Place the extra width of the lines 
entirely below the lines already drawn. For the method of 
drawing these lines see "Shade Lines." 

Do not draw the heavy lines to the boundaries. After all 
are drawn, place the triangle vertically and fill in the spaces 
left with a fine opening of pen. 

Beginning with the sixth line from the top, for a length of 
2" on the left ends of the lines make lines that correspond in 
total width to those on the right, but leave a narrow strip of 
white along the middle of the width. This is the effect used in 
boiler and ship-building work to show that two plates are 
together at the line of demarkation. 

Make the edges sharp with a fine opening of pen, and fill in 
with a coarse opening of pen. 

The center line is drawn when the red-ink work is done. 



F/A'ST DRA WINGS. 



"3 



Sheet I. Fig. 4. 

Scale lo. Inches divided into tenths. 

Vertical heavy lines. 

T square ; triangular scale ; triangle ; full lines, of varying 
widths when inked. 

Pencil-work. — From one of the top corners lay off hori- 
zontally the following distances, each distance measured from 
the corner: V075 ; V225 ; 7450; '.'75 I i'.'i25; 1V575 ; 2'.'io; 
2'.'625. The remaining distance is "375 for a check. 

Draw a horizontal center line and vertical lines through 
each of the points marked. 

Ink- work. — Draw the boundary lines and the lines through 
the marked points. These lines are fine lines. Make the 
upper halves of the lines of increasing width, as in Figs. 3 and 
4. The left boundary line is the fine line already drawn. 
Place the extra width of the lines entirely beyond the original 
lines from the original point of measurement. 

Beginning with the sixth line from the left, for a length of 
'.'5 from the bottom draw lines as wide as for the upper half 
of the figure, but leave a narrow central strip of white. 

These heavy lines will have to be squared at the ends by 
using the R. L. pen along the T square. 



114 



MECHANICAL DRAWING. 



The right-hand and lower boundaries of the figure are 
shaded. 

The center line is drawn when the red-ink work is done. 




Sheet I. Fig. 5. 

Scale, 2" = I foot, or one-sixth size. 

45° triangle. 

T square ; triangular scale ; triangle ; full lines, of varying 
widths when inked. 

Pencil-work. — Draw the diagonals. From the N. W. and 
S. E. corners of the figure measure the following distances on 
the diagonal towards the center, each distance measured from 
the corners: %" ; %" ; 1%" ■ 2%"- ^Y^" ; ^%" • 7"; 9";, 
11}^". The remaining distances are each i^", which is a 
check. 

Through these marked points draw lines parallel to the 
other diagonal of the figure. 

Ink-work. — Draw the boundaries of the figure and the lines 
through the marked points with a fine pen. Beginning with 
the lines nearest the corners make half of each successive line 
heavier than the preceding in about the proportion of Figs. 3 
and 4. The two lines nearest to the center are made heavy 



FIRST DRAWINGS. 



115 



all the way across. The weight of the lines is towards the 
center. 

The diagonal lines are in red ink and are drawn when that 
kind of inking" is done. 




Sheet I. Fig. 6. 

Scale, full size. 

45° triangle. 

T square; 45° triangle; full lines in pencil and ink; shade 
lines. 

The figure represents blocks resting centrally on each 
other, the smallest on top. 

Pencil-work. — Center the figure and draw as shown, using 
only the T square and the 45° triangle. 

The checks on the work are the inscribed circles, as shown. 

Ink-work. — The lines are all of equal width and distinctness, 
but fairly heavy. 

The construction and check lines are drawn in red ink. 

The blocks are shaded according to remarks under '• Shade 
Lines." 

Carefully choose a width of line, not too heavy, and do not 
change the pen when shading. 



ii6 



MECHANICAL DRA WING. 



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Sheet I. Fig. T. 

Scale, I" = I foot, or one thirty-second size 

60° triangle. 



T square ; triangular scale ; triangles ; full lines of varying 
widths, pencil and ink; shade lines. 

The figure represents blocks resting centrally on each, 
other, the smallest on top. 

Pencil-work. — Center the figure with the 45° triangle laid 
along the T square. With the 60° triangle laid along the T 
squa.re draw lines making angles of 60° with the horizontal 
through the center of figure. 

From the extremities of the horizontal center line draw 
lines making angles of 60° with the horizontal, and extend them 
to cut the lines last drawn. Through these intersections draw 
horizontal lines. This forms a hexagon. 

Through the central point of the figure draw a line at 30° 
with the horizontal, and extend it to cut one side of the 
hexagon. This line will be at right angles to the side of the 
hexagon. Beginning at the side of the hexagon, measure to 
scale towards the center of figure along the line last drawn the 
following distances, each distance measured from the side of 
the hexagon: 2" \ 4"; 7"; \\" \ 16"; 2.^" \ 2 ft. 5''; 3 ft. 1" .. 



FIJ^ST DRAWINGS. 



117 



Through these points draw Hnes parallel to the side of the 
hexagon from which the distances were measured. Carry 
these lines around the figure. 

They make a number of hexagons within the original 
hexagon. 

Portions of circles are drawn with the bow spacers as far 
as they can be used, and after that with the compasses through 
the extreme points of each hexagon, as a check. 

The center of figure is the center from which these circles 
are drawn. 

Ink-work. — The only black lines are those of the boundaries 
of the figures and the hexagons. All lines at angles of 60'' 
and 30° that are used in construction, as well as the lines for 
centering the figure and the vertical and horizontal center lines, 
are drawn in red ink. The arcs are also in red ink. 

Place shade lines on the blocks. Take care that the heavy 
portion is outside the original line. 




Sheet I. Fig. 8. 

Scale, f" = I foot, or one-sixteenth size. 

60° triangle. 



Il8 MECHANICAL DRAWING. 

T square ; triangular scale ; 60° triangle ; full lines in pencil 
and ink ; shade lines. 

The figure represents several 60° triangles. 

Pencil-work. — Center the figure and draw the vertical 
center line; draw lines through the center making 60° with 
the horizontal. Draw the triangles in position, as shown. 
The distances between the outer edges and the openings in the 
triangles is on all sides 3" to the scale given. 

Checks for the work are circles drawn with the center of 
figure as a center through the corresponding points of the tri- 
angles. 

Ink-work. — No construction lines are drawn. After the 
triangles are drawn, the proper edges are shaded in accordance 
with directions under " Shade Lines." 

The vertical center line is extended beyond the figure in 
red ink. 

The check circles are fine lines in red ink. 



FIEST DRA WINGS. 



119 




Sheet I. Fig. 9. 

Scale, i" ^ I foot, or one-twelfth size. 

45° triangle. 



T square; triangular scale; 45° triangle; full lines, pencil 
and ink; shade lines. 

Same as Fig. 7, substituting 45° triangle. Width of sides 
of triangle two and one-quarter inches to scale given. 

Extend both horizontal and vertical lines beyond the figure 
in red ink. 

CJieck circles are drawn as for Fig. 8. 



I20 



MECHANICAL DRA WING. 




Sheet I. Fig. 10. 

Scale, full size. 

45° and 60° triangles. 



T square; triangles; full lines of varying widths, pencil and 
ink. 

Pencil-work. — Draw the diagonals. With the 45° triangle 
in position on the T square and the 60° triangle resting against 
the 45° triangle, draw the figure for all four quadrants. The 
checks for accuracy are circles drawn with the center of figure 
as the center and radii for corresponding points. 

Ink-work. — The diagonals and check circles are drawn in 
red ink. 

The black-ink lines gradually increase in width from the 
corners to the center — corresponding lines of equal weight. 

The extra weight of the lines is equally divided on either 
side of the orierinal line. 



FII^ST DRAWINGS. 



121 




Sheet I. Fig. 11. 

Scale, full size. 

45° and 6o° triangles ; no T square. 

Triangular scale; 45° and 60° triangles ; full lines, pencil 
and ink. Shade lines. 

All lines are drawn with triangles only as guides. 

The figure shows small blocks of equal heights. Those in 
the center are pushed together. 

Pencil-work. — Draw the diagonals, horizonal and vertical 
center lines. 

From each corner measure i" on one side only of the 
boundary, and from the points marked draw lines perpendicular 
to the diagonal at the nearest corner. From the extremities 
of these last drawn lines draw lines within the figure making 
angles of 30° with them. These lines should meet on the 
diagonals. Check circles are drawn with the center of figure 
as a center and radii to the last points found. 

From the center of figure draw lines on both sides of the 
diagonals making angles of 30° with them ; this makes four 
continuous lines through the center. Measure on one of these 
lines only a distance of ^". Begin at the point marked and 



122 



MECHANICAL DRAWING. 



complete the figure abed, etc., by drawing lines parallel to the 
diagonals and to the center lines. The last line drawn should 
pass exactly through the original point. A cJieck circle is 
drawn with 6^ as a center and should pass through all these 
points. 

From abe, etc., draw lines outside the figure already drawn 
making angles of 60° with the lines ab, ed, etc., extending 
these lines to meet the nearest horizontal or vertical center 
lines. A check circle is drawn through the meeting-points of 
each pair of these lines. 

Ink-work. — The lines, except check circles, diagonals, and 
center lines are solid ink-lines made with a fair opening of the 
pen. All are of equal width. After all the lines are drawn, the 
figure is shaded according to directions under " Shade Lines." 

The check circles, diagonals, and center lines are drawn 
in red ink. 




Sheet I. Fig. 12. 

Scale, 4" =r I foot, or one-third size. 

60° triangle. 

T square ; triangular scale ; 60° triangle ; full lines in 
pencil, full and broken lines in ink. 



FIRST DRAWINGS. 1 23 

Pencil-work. — All lines are full lines. 

Using the scale given mark off the lines AB and CD into 
lengths of \" , and the lines AC and BD into lengths as follows: 
AE = BG = CF ^ DH = i}i". Divide these lines into 
spaces y?," long. Divide the lines EF and GH into spaces 
yi" long. 

From the divisions of AB draw lines at angles of 30° with 
the T square. 

From the divisions of CD draw lines at angles of 60° with 
the T square. 

The triangles are laid along the T square, and lines are 
drawn from left to right always. 

The vertical center line yK is a check on the work. 

From the divisions of AE, EC, BG, and HD draw lines at 
angles of 30° with the T square. From the divisions of EF 
and GH draw lines at angles of 60° with the T square. 

The horizontal center line LAIis sl check, as all the inter- 
sections should be on that line. 

Ink-work. — Draw full lines as fine as the pen will maintain 
from the divisions oi AE and FC to the horizontal center line. 

Draw broken lines as fine as those above from the divisions 
of BG and HD to the horizontal center line. 

Draw full lines from the divisions of GH to the horizontal 
center line, the lines to be fully twice as broad as the lines 
previously drawn — noting that the lines are made broken where 
they come in contact with the previously completed full lines. 

Draw broken lines from the divisions of EF to the horizon- 
tal center line, the lines to be of the width of those just com- 
pleted. 

Draw full lines from the divisions of AB to the vertical 
center line, the lines to be four times as broad as the lines first 
drawn . 

Draw broken lines from the divisions of CD to the vertical 
center line, the lines to be of the same width as the lines last 
drawn. 



124 



MECHANICAL DRAWING. 



The lines JK and LM, the center lines, are drawn in red 
ink later. 




Sheet I. Fig. 13. 

Scale, full size. 

Bow spacers . 

T square; 45° triangle; bow spacers; full lines in pencil, 
full and broken lines in ink. 

Pencil-work. — Draw the diagonals. These should check 
exactly with the 45° triangle laid along the T square. 

With the bow spacers, space by trial (see "Bow Spacers") 
each of the half-diagonals into nine parts, and draw full lines 
through each point parallel to the other diagonal, using the 
45° triangle sliding along the T square. For the lines running 
S. E. and N. W. draw from the N. W. point; for those run- 
ning N. E. and S. W. draw from the S. W. point. In dravv^- 
ing lines parallel to AD, begin with that nearest B] for lines 
parallel to CB, begin with that nearest A. 

Do not take time to begin and stop the lines at the boun- 
daries. 

With the bow spacers divide each space of OC and OD into 
three parts and draw full lines as before. 



FIRST DRAWINGS. 



125 



E and F are at five of the original spaces from the center. 

Divide the spaces of EC and ED into two parts with the 
bow spacers and draw Hnes as before. 

Note that in this figure the Hnes that are to be broken lines 
when inked are not drawn broken in the pencil-work. 

Ink-work. — In inking, set the pen for a line that is not the 
finest that the pen will make, but as fine a line as the pen will 
maintain and keep the ink running freely without clogging. 

Draw the lines parallel to AD full lines and those parallel 
to BC broken lines, varying the lengths of the dashes from 
y^" long for the lines farthest apart to y^g" long for those 
nearest together. 




Sheet I. Fig. 14. 

Scale, full size. 

Dividing lines into parts. 

T square; triangle; bow spacers; full lines in pencil, full 
and broken lines of varying widths in ink. 

Pencil-work. — Divide each boundary line of the figure into 
four, five, or six parts by laying off from each corner any line 
at a small angle with one of the boundaries of the figure, and 
spacing off for four, five, or six times any convenient distance 



126 



MECHANICAL DRAWING. 



with the bow spacers ; connect the last points marked with the 
nearest corner as shown, and draw Hnes from the other points 
parallel to this line. 

Use a different distance with the bow spacers in each of the 
four cases. 

Connect all the divisions of the side lines with the opposite 
corners in full lines. 

Ink-work. — The black-ink lines are varied as shown: one 
set, broken lines; one, fine full lines; the other two, full lines 
of different widths. 

The construction lines are drawn full in red ink after com- 
pleting- the other lines. 




Sheet I. Fig. 15. 

Scale, y = I foot, or one twenty-fourth size. 

Dimension lines and figures. 



Triangular scale; triangles; full lines in pencil, full and 
broken lines in ink ; dimension and dimension projecting lines ; 
dimensions. 

Pencil-work. — Find the middle points of the top and bottom 
lines of the figure. 



FIRST DRAWINGS. 12/ 

From the middle point of the bottom line measure in each 
direction the following successive distances: two of 2''; two of 
ly^' \ two of i" \ two of 3>^''; two of 4''. The remaining 
distances to the corners should be 6 ' each for a check. 

From the middle point of the top line measure in each 
direction the following successive distances: one of 7^"; one 
of 8"; one of 9^'^; and one of 11''. These last dimensions 
should mark points coinciding with corners of the figure. 
From the upper corners measure downwards the following suc- 
cessive distances: HJ^"; I2>^"; 10%"; 8}4"; 6}4" ; ^y. 
The distances from these last measured points to the lower 
corners should be each 16" for a check. 

From all the points marked off on the bottom line in 
sequence draw lines on the same side of the vertical center line 
to the points marked off on the top and side lines in sequence. 

Begin at the bottom and lay off on the vertical center line 
the following successive distances: 22^''; 2 ft. ^y^." ', 20". 
This last distance should just reach to the top line. 

Through these points marked on the vertical center line 
draw lines from all four corners of the figure, and measure to 
the nearest quarter inch to the given scale the distances from 
the points where these last lines cut the boundaries of the figure 
to the nearest corner. 

These dimensions, when placed on the drawing at the end 
of the inking, are checks for the accuracy of the last part of the 
work. 

Ink-work. — Ink the first set of lines with fine full lines ; ink 
the lines through the points on the vertical center line with fine 
broken lines, with dashes about yi" long. 

The measurements required are placed on the figure after 
all the figures are completed. Dimension and dimension pro- 
jecting lines are used. See the notes under "Dimension 
Lines. " 

The vertical center line is in black ink to the boundaries of 
the figure, and extended in red ink about y^" above and below. 



128 



ME CHA NIC A L DRA WING. 




Sheet I. Fig. 16. 

Scale, full size. 

Section: Hatching. 



T square ; triangles ; bow spacers ; full lines, pencil and 
ink ; shade lines ; hatching. 

The figure represents a horizontal section through a piece 
of cast iron, the iron resting on the lower block. 

Pencil-zvork. — Divide one top and one side boundary line 
into six parts each by drawing lines from a corner at an angle 
and using the bow spacers and a different spacing length for 
each. 

Draw the horizontal and vertical lines, running them, 
entirely across the figure. Do not hatch in pencil. 

Ink-work. — Draw the figure in fairly wide black-ink lines. 

Begin at the N. W. corner and hatch the figure with lines 
at an angle of 45°, from S. W. to N. E. 

The line used for hatching is not the finest the pen may 
make, but is as fine a line as can be depended upon. Do not 
fail to make every line of the hatching just as distinct as if it 
were a line of the fisfure. 



FIKST DRAWINGS. 



129 



When a line of the hatching is begun and ends at a space, 
the same Hne is continued beyond the space if it would cut the 
figure farther on. 

Shade the figure according to remarks under "Shade 
Lines. " 

Refer to remarks under ' ' Hatching. ' ' 

The lines used in dividing the boundaries into spacers are 
inked in red ink. 

Draw center lines in red ink. 




Sheet I. Fig. 17. 

Scale, full size. 

Line shading. 



T square; 45" triangle; full lines, pencil and ink; shade 
lines; line shading. 

The figure represents bands of metal interlaced, with line 
shading for the flat surfaces to make the figure clearer. 

Pencil-work. — As in the preceding figure, divide the sides 
into six parts; using the 45° triangle draw the intersecting 
lines as shown, but make them continuous across the figure. 

hik-work. — Before inking, it is well to make small marks 
to identify at least one of the longer bands, as, for instance, the 



130 



MECHANICAL DRAWING. 



longest one running from N. W. to S. E. With this one 
clearly marked there should be little trouble in following the 
figure without error. Draw all the lines at one angle first, then 
the others. 

Put shade lines on the edges requiring shading. 

Line-shade the strips. Those from the N. E. to S. W. 
shade with light lines, those from N. W. to S. E. with heavier 
ones. These lines are equally distant apart, and about eight 
are placed on each strip. 

The construction lines for dividing the boundaries are inked 
as full lines in red ink. 




'MV^ 



Sheet I. Eig. IS. 

Scale, i^" = I foot, or one-eighth size. 

Protractor. 



Triangular scale ; T square ; triangles ; protractor ; full 
lines in pencil, full and broken lines in ink. 

Pencil-zvork. — Draw the vertical center line. From the 
middle point of the bottom line on each side lay off the follow- 
ing successive distances horizontally: i"; i^"; i^''; ^H"f 
2"; 21^". The remaining distance is 2]4" for a check. 



FmS T DRA WING S. 1 3 1 

Beginning at the top corners, measure off downward on the 
side boundary Hnes the following distances, measuring in each 
case from the top corners: ^"; zY^" \ 8^"; iiyi" \ ^7}i"\ 
23". The re77iaining distance on each side is \" . 

Connect the points laid off* on each side from the bottom 
center with those laid off from both the top corners in succes- 
sion on each side. Measure the acute angles made by these 
lines with the bottom line to the nearest quarter degree, or 
15 min. See "Protractors." 

The average of the measurements of the two corresponding 
angles on the two sides of the center line is marked on one of 
the angles after finishing all the figures. 

In order to measure these angles, it is necessary to extend 
most of the lines in pencil beyond the limits of the figure ; this 
is done with fine lines so that the extra portions may be readily 
erased. 

Lay off from the top central point on each side lines 
making with the top line the following angles: 3>^°; 11° 15'; 

23° 45'; 36°; 50° 15'; 62° 75'- 

In laying off these angles, do not go around the drawing- 
board ; remain in the usual place. 

Ink-work. — Draw all the first lines full lines as fine as the 
pen will sustain ; draw the lines laid off with the help of the 
protractors in fine broken lines. 

The center line is a black-ink line like the others to the 
boundaries and is extended in red ink half an inch above and 
below. 

The arcs for m.easuring angles are drawn in red ink and 
spaces are left for figures except where the drawing is too 
crowded ; in this case draw an arrow to a convenient point 
outside the figure and place the reading of the angle there. 
Place the figures for the angles vertical. This is done because, 
if they were placed according to rule — at right angles to the 
dimension lines — they could not be read from the proper angle 
of the board. 



132 MECHANICAL DRAWING. 

Place the average readings of the corresponding angles on 
one side only of the vertical center line. According to sizes 
place alternate readings of angles on each side of the vertical 
center line. 

Legend. — The legend reads: 

SHEET I. 

STRAIGHT-LINE DRAWING. 

Name [F. K. Jones.] Class [Fourth Class.] 

Date [Dec. i, 1900.] 

The space to be used is divided and the sizes of the 
lettering arranged by each one according to his judgment. 
" Sheet I " and "Straight-line Drawing " are made in block 
letters of two different types, but of straight lines only. The 
remainder of the legend except the name is made in ' ' free- 
hand lettering." The name is an autograph. 

Above each figure the number of the figure is centrally 
placed, as Fig. I, Fig. 2, etc., in "free-hand lettering." The 
bottom line of the lettering is yi" above the top of the figures. 

The scale is centrally placed below each figure, the bottom 
line of the lettering y%" below the bottom of the figure. This 
is also ' ' free-hand lettering. 

The effect is improved by drawing moderately heavy black 
lines just under the lettering. 

Border Line. — After the lettering is completed, the border 
line is drawn. See " Border Line." The drawing is cleaned 
and finally inspected. It is then cut from the board and paper 
is stretched for the next drawing. 



SHEET 11. 



CIRCLES: TANGENTS: ARCS MEETING ARCS: IRREGULAR 
CURVES: SHADING ARCS: FILLETS. 

Lay out the Sheet and follow the directions for Sheet I. 
Do not sketch the general plan of the Sheet, as it is the same 
as Sheet I. 




Sheet II. Fig. 1. 

Scale, full size. 

Compass. 

T square; triangles; compasses; same radius for all circles; 
full lines in pencil and ink ; varying widths of lines in ink-work. 
See remarks under " Compasses." 

133 



134 MECHANICAL DRAWING. 

Pc7icil-work. — Center the figure by drawing diagonals. 
Use the center of figure as a center and a radius to the middle 
point of one side and draw a circle. Take care to properly 
bend the knees of the compass. This circle should exactly 
touch the boundaries at the middle points. 

Begin at the middle point of the left-hand boundary line 
and with the same radius as before draw an arc ending at the 
boundaries of the figure. Use the point where this arc cuts 
the first circle drawn as a center and draw another arc ; and 
so on around until the last arc drawn passes through the first 
center used on the left. Every one of these arcs should pass 
exactly through the center of figia^e. 

From each of the corners of the figure and from the remain- 
ing middle point of the side as centers draw arcs. Those 
drawn with the corners as centers should pass exactly through 
the middle points of the sides and those drawn with the middle 
points of the sides as centers should pass exactly through the 
center of figure and the corners. 

Ink-work. — Set the pen for the first circle and first set of 
arcs drawn. Make this a fair line — not as fine as the pen will 
make — and draw a sample line on the margin of the paper 
where others may be compared with it at will. Draw the first 
circle. Draw the arcs until they end at the first circle. 

Set the pen for the other arcs, making the sample line four 
times as heavy as the first sample line. Draw the arcs that 
have the corners as centers, extending them to the boundaries. 
Draw the arcs that have the middle points of the sides as 
centers only where they extend beyond the first circle drawn. 
As some of these arcs begin to be heavy at the original circle 
and are light inside of it, care must be taken to begin the heavy" 
part exactly at the circle. Note also that some of these arcs 
do not extend within the circle at all. Arrange the extra 
width of the lines so that it does not pass beyond the boun- 
daries. 

Go over the first circle again with the wider line; arrange 



FIRST DRAWINGS. 



135 



the extra width so that it does not pass beyond the boundaries 
of the figure. 

Draw the diasfonals and the center lines in red ink. 




Sheet II. Fig. 2. 

Scale, 4" = I foot. 

Compasses, bow pencil, and pen. 

T square ; triangles ; triangular scale ; compasses ; bow 
pencil and pen ; full lines, pencil and ink, varying widths in 
ink. 

Pencil-zvork. — Center the figure. Draw the center lines. 
From the middle point of the top boundary line measure down- 
ward the following dimensions: %" \ H" ; lyi"; i^''; 2)4"; 
2)}i" ; 4}i"- The remaining distance to the center is %" . 

Using the bow pencil (see notes under "Bow Pencil") 
with the center of figure as a center draw circles through each 
of the points marked. 

From one corner of the figure measure along the diagonal 
the following dimensions : wyi" \ 11^"; \iY\" \ '^2%". 

Using the compasses with the center of figure as a center, 
draw arcs through the points marked, extending them to 
meet the boundaries. 



136 



MECHANICAL DRAWING. 



Ink-work. — Using- the bow pen (see notes under "Bow 
Pen"), draw the smaller circles. Make the outer one — that 
tangent to the boundaries — a heavy line and the others 
gradually decreasing in width to the inner one, which should 
be as narrow a line as the pen will make. Place the extra 
width of line on either side of the pencil-line. 

Using the compasses, draw the outer arcs, decreasing the 
-widths of the arcs as each arc becomes more distant from the 
line tangent to the boundaries, and in the same manner as for 
the inner lines. 

Draw the diagonal used and the horizontal and vertical 
center lines in full lines with red ink. 




Sheet II. Fig. 3. 

Scale, full size. 

Bow pencil and pen. 

T square ; triangles ; triangular scale ; bow pencil and pen ; 
full lines in pencil, full and broken lines in ink. 

Pencil-work. — Draw the center lines. Divide each of these 
lines into six parts by any method and draw vertical and hori- 
zontal lines through these divisions. Draw arcs as shown, 
using a radius equal to the length of the diagonal of two 
adjacent squares. Take time in getting the exact radius by 



FIRST DRAWINGS. 



137 



trial at several points and do not change this radius while 
drawing the arcs. 

Ink-work. — Set the pen as exactly to the correct radius as 

possible and do not change the setting while drawing the lines. 

Make the lines quite fine. Draw every other pair of arcs full 

lines and the remaining ones broken lines with dashes about 

1 " lono" 

After all the arcs are drawn, go over the top and bottom 
rows of full lines, making them about four times as heavy as 
before, keeping the extra width of line within the boundary 

lines. 

Draw the vertical and horizontal lines in red ink. 




Sheet II. Fig. 4. 

Scale, full size. 

Bow pencil, bow pen, bow spacers. 

T square; triangles; bow spacers; bow pencil and pen; 
full lines in pencil and ink, heavy lines in ink. 

Paicil-work. — Divide the top and one of the vertical sides 
into six parts by drawing lines at an angle and spacing off dis- 
tances, using different lengths of space for the two lines. 

Draw vertical and horizontal lines through these divisions ; 
draw diagonal lines for the figure and lines parallel to them 



138 



MECHANICAL DRAWING. 



from the points marked off. Use the intersections of these last 
lines as centers and draw circles tangent to the vertical and 
horizontal lines. By trial of a few spaces decide on the radius 
that will bring the closest approximation to the correct one for 
all the spaces and use that radius for all. 

Ink-zvork. — Draw all the circles in fine lines and make the 
alternate ones, as indicated, heavy circles. These lines of the 
circles are ^^" wide, and the thickness is on the inner side of 
the line first drawn. Draw the outer and inner circles quite 
heavy and fill in by changing the set of the bow pen and open- 
ing the points wide. 

Draw the auxiliary lines used for dividing the sides into 
equal parts and the lines for marking the centers of the circles 
full lines in red ink. The vertical and horizontal lines are 
drawn in black ink and are fine lines. 



Sheet II. Fig. 5. 

Scale, 2" = I foot. 

Fillets. 

T square ; triangles ; triangular scale ; bow pencil and pen ; 
full lines in pencil, full and broken lines in ink. 

Petuil-work. —T)rdLVj the center lines. On the horizontal 



FIRST DRAWINGS. 139 

center line measure from the center to right and left the fol- 
lowing dimensions : lYz" \ 2%"\ 4^''; 6"\ 7%"; 8}{"; <^" . 

On the vertical center line measure from the center upwards 
and downwards the following dimensions: 2}(" \ 4"; SH'^'> 
6H"; VA"\ 8^"; 9"- 

Construct rectangles with the use of the T square and tri- 
angles on the corresponding measurements. Connect the 
corners of the rectangles with small arcs or "fillets," as fol- 
lows : 

For the N. E. corners, use radii in succession, beginning 
with the inner rectangle, as follows: y^' \ i" ; lyi"; 2"; 2}4" ; 

3"; VA"- 

For the N. W. corners, as before, use the following radii: 

y^"; 1%"; ly"; 2%" ■ 2y" ■ yy"; ^y". 

For the S. W. corners, as before, use the following radii: 

I"; lyy- 2"; 2y"- 3"; ^y"] 4"- 

For the S. E. corners, as before, use the following radii: 

^H"\ ^Ya"; 2K"; 23/"; 2>}i"; 3K"; aH"- 

In drawing these fillets, from the corner of the rectangle 
swing an arc around of the correct length to cut the adjacent 
sides of the rectangle. From these points swing arcs of the 
same radius to meet each other. These last points are the 
centers from which to draw the fillets. 

Many draftsmen of experience do not take the trouble to 
define these centers, but find them rapidly and accurately by 
trial . 

Carefully draw all these fillets with the bow pencil. Mark 
the centers clearly. Swing the arcs beyond the points of tan- 
gency, as it is impossible to determine that the arc is exactly 
right if it stops on the line. 

Ink-work. — Ink all the fillets first with comparatively fine 
lines. The upper half of the figure is drawn in full and the 
lower half in broken lines with dashes varying according to the 
size of the rectangles. 

In inking the straight lines, carefully set the bow pen for 



I40 



MECHANICAL DRAWING. 



the first line to agree with the Hne of the fillets. Draw the 
vertical lines first one after the other, beginning at the left. 
Always draw from the fillet at the left hand towards the one 
at the right and stop the line near the fillet and draw a line 
from the right-hand fillet to meet the previously drawn line. 
This allows of a slight moving of the pen from or towards the 
triangle or T square to meet the other line fairly. This case 
of drawing a straight line to meet two curves is the only one 
where it is advisable to break the general rule of drawing from 
left to right. 

Draw the center lines in red ink, and show in red ink in 
one corner of one rectangle only the method of finding the 
center of the fillet. 




Sheet II. Fig. 6. 

Scale, f" = I foot. 

Arcs and straight lines. 

T square ; triangles ; triangular scale ; bow pencil and pen ; 
full lines in pencil, full and broken lines in ink. 

Pencil-zvork. — Draw the diagonals. From one of the lower 
corners of the figure measure along the diagonal the following 
distances, each measured from the corner: 2" \ j" \ 16"; 2 ft. 
3"; 3 ft. 5"; 4 ft. 10". 



FIRS T DRA WINGS. 1 4 1 

Begin with the corner as a center and draw an arc, using 
the first dimension as a radius ; using this first point measured 
as a center and the distance ft-om that point to the second one 
as a radius, draw another arc ; repeat this operation for all the 
points measured on the diagonal. These arcs are drawn as 
complete circles, though all of the circumferences are not drawn 
in ink. 

From the same corner measure along each of the sides 
adjacent the following dimensions, each measured fi-om the 
corner: 2>4"; lo''; 15"; 23"; 2 ft. 11"; 4ft. 

From the adjacent corners measure towards the first corner 
these same last dimensions. 

From each of the measurements taken from the first corner 
along the sides of the figure in succession draw tangents to the 
arcs drawn in succession, the first tangent being drawn fi-om 
the first measurement to the first arc, etc. 

From each of the measurements made from the other two 
corners in succession draw tangents to the arcs in succession, 
the first tangents being drawn from the first measurements to 
the last arcs drawn, etc. 

Note. — Always draw the tangent away from the arc, not 
towards it. 

These tangents are drawn by trial, using a triangle. There 
is no attempt made to find the point of tangency. 

From the center of figure towards the corner of the figure 
diagonally opposite the first corner used, measure along the 
diagonal towards that corner the following dimensions, each 
measured from the center of figure: 3^'; 8"; 14"; 21"; 2 ft. 
5"; 3 ft. 2"- 4 ft. I". 

Begin with the center of figure as a center and draw an arc, 
using the first dimension as a radius; using the first point 
measured as a center and the distance from that point to the 
second one measured as a radius, draw another arc ; repeat this 
operation for all the points measured on the diagonal. Using 
the last point measured as a center and such a radius as will 



142 MECHANICAL DRAWING. 

make the arc tangent to the two adjacent boundary Hnes of the 
figure, draw an arc. These arcs are drawn as complete circles, 
though all of the circumferences are not inked. 

From the center of figure measure along each part of the 
diagonal which is at right angles to the one along which these 
last measurements were made, the following dimensions: 3"; 
5"; 10"; 2\" \ 2 ft. 9"; 3 ft. 10"; 5 ft. \". 

From each of these last measurements in succession draw 
tangents to each of the arcs last drawn in succession, the first 
tangents being drawn from the first measurements to the first 
arc, etc. These tangents are on the same side of the diagonal 
as the point. 

From each of these last measurements in succession draw 
tangents to each of the arcs last drawn in succession, the first 
tangents being drawn from the first measurements to the last 
arc, etc., the final tangents to the smallest arc being drawn 
from the corners of the figure. Tangents as above. 

These tangents are drawn as before, by the use of the tri- 
angles only, with no attempt at finding the points of tangency. 

Ink-work. — Use a fine pen. 

Draw the first set of arcs in full lines, extending them only 
to the points where the tangents meet them. From these arcs 
draw the first set of tangents in full lines to the boundaries. 

Draw the second set of tangents from these arcs in broken 
lines with dashes about ■^-^" long, extending them to the 
boundaries. 

Draw the second set of arcs in broken lines, the lengths of 
the dashes as before, and extend them as before only. 

From these arcs draw the first set of tangents in full lines 
to the diagonal only. 

From these arcs draw the second set of tangents in broken 
lines, extending them to the diagonals. 

Draw the diagonals in red ink. 



FIRST DRAWINGS. 



143 




Sheet II. Fig. 7. 

Scale, y =■ I foot. 

Two arcs and straight line joining them. 



T square ; triangles ; triangular scale ; bow pencil and pen ; 
connecting tangents with arcs; full lines in pencil, full and 
broken lines in ink. 

Pencil-work. — Draw the center lines. 

With centers on the horizontal center line, draw arcs tangent 
to the side boundary lines at the middle points with the follow- 
ing radii: 2 ft. 6%"\ 2 ft. 3"; I ft. gy^"; I ft. 2%"; 8''; 2". 

Connect these corresponding arcs above and below the 
horizontal center line with straight lines, using the triangles 
only. Draw a line away from the left-hand arc and extend it 
to near the other arc ; then break the established rule of draw- 
ing lines from left to right and draw a line away from the 
right-hand arc to connect with the line already drawn. 

The T square moved up and down the board is a check on 
the work. 

With centers on the vertical center line draw arcs tangent 



.144 MECHANICAL DRAWING. 

to the top boundary line at the middle point with the following" 
radii: 2 ft. 8"; 2 ft. 4''; i ft. lO)/^" ; i ft. 3"; 8>^"; 3^'. 

Connect these arcs with tangents to the nearest bottom 
corner of the figure on the same side of the vertical center line. 

With centers on the vertical center line draw arcs tangent 
to the bottom boundary line at the middle point with the fol- 
lowing radii: 2 ft. 9"; 2 ft. 5"; i ft. wyi" \ i ft. 4"; 9>^"; 

Connect these arcs with tangents to the farthest top corners 
of the figure on the further side of the vertical center line. 

The T square carried down the board is a check on the 
accuracy of the work, as the points of tangency on the sides 
of the vertical center line for any arc should be on a horizontal 
line. 

Carefully draw tangents from arcs. 

Ink-work. — Draw the first set of arcs and tangents in full 
lines, making the inner one a fine line and increasing the width 
of the other lines as the radii increase. 

Draw the set of arcs that are tangent to the top line and 
their connecting tangents as fine broken lines with dashes 
about i^" long. 

Draw the set of lines that are tangent to the bottom line 
and their connecting tangents as broken lines twice as heavy 
as those previously drawn, but with the same length of dashes. 

Draw the vertical and horizontal center lines in red ink. 



FIRS T DRA WINGS 



145- 




Sheet II. Fig. 8. 

Scale, full size. 

Protractor, arcs, and straight lines. 

T square ; triangles ; triangular scale ; protractor ; full lines 
in pencil, full and broken lines in ink. 

Pencil-work. — From the two bottom corners lay off upward 
from the bottom line and within the figure the following angles : 
5°; 11°; i8° 30'; 27°; 36° 30'; 48°; 60° 30'; 74°; 88^ 30. 

Join seven of the corresponding pairs of lines with tangen- 
tial arcs of the following radii in succession, beginning with the 
lines drawn from the smallest angles : 2", i^''; i^^"; i^^"; 
i"; y\" \ y^." • For the next set of lines use a radius that will 
make the arc tangent to the two lines and to the top boundary 
line. For the last set of lines, use a radius of y^" and draw 
arcs tangent to the lines and to the top boundary line. 

The centers are found by trial. 

From the two top corners lay off downward from the top 
line and within the figure the following angles: 6° 30'; 12°; 
19°; 28° 30'; 37°; 49° 30'; 61°; 7S°; 89°. 

Join seven of the corresponding pairs of lines with tangen- 



146 



MECHANICAL DRAWING. 



tial arcs of the following radii: i^"; \y^" \ i^''; \" ; yi' ; 
yz" ', %" ■ Finish the two remaining sets of lines as be- 
fore. 

The centers are found by trial. 

Ink-work. — Ink all the arcs first and draw the straight 
lines away from the arcs. Make the set of lines from the lower 
corners and corresponding arcs in fine full lines and those from 
the top corners in equally fine broken lines with dashes about 
}i" long. 

Draw the vertical center line in red ink. 




Sheet II. Fig. 9, 

Scale, 10. 

Tangent arcs. 

T square ; triangles ; triangular scale ; compasses ; bow 
pencil and pen; full arcs in pencil, full and broken lines in ink. 

Pencil-zvork. — Center the figure and draw center lines and 
diagonals, extending these lines beyond the boundaries of the 
figure about 3". 

From the center of figure measure on one of the center lines 
in one direction only the following dimensions: '/50; '.'75; \" \ 
1-25; 1:75; 2'/25; 3"; 4". 



FIRST DRA WINGS. 



H7 



With the bow pencils and compasses, swing these dimen- 
sions around the central point and mark them on the other side 
of the center line used and on both sides of the center line not 
first used. 

With these points as centers draw arcs tangent to the 
adjacent diagonals, extending them just enough beyond the 
diagonals to ensure their tangency. These radii are determined 
by trial only. 

Checks for the work are circles drawn with the center of 
figure as a center and radii to the points of tangency of corre- 
sponding arcs on the diagonals. 

Ink-work. — Draw the arcs from diagonal to diagonal only 
in fine lines. The two sets of arcs on the sides and the one 
set above the center are full lines; the lower set of arcs is 
drawn in broken lines with dashes about -y^" long. 

Draw the auxiliary and check lines in red ink to the 
boundaries only. 




Sheet II. Fig. 10. 

Scale, I" = I foot. 

Connecting arcs. 



148 



MECHANICAL DEA WING. 



T square; triangles; triangular scale; bow pencil and pen; 
compasses; connecting arcs with each other; full lines in 
pencil and ink, full and broken lines in ink. 

Pencil-work. — Center the figure and draw the center lines. 
With the center of figure as a center and the following radii 
draw semicircles in the upper part of the figure ending on the 
horizontal center line : 2" \ 4>^"; 7/^''; n''; 15"; I9>^"; 24". 

With the extremities of the horizontal center line as centers 
draw arcs connecting with each end of those previously drawn, 
extending them to the boundaries of the figure. 

With the four corners of the figure as centers draw arcs 
from the points where the last arcs cut the vertical sides of the 
figure, extending these arcs to the boundaries. 

Ink-work. — Draw the first set of lines and the connecting 
lines in fine ink lines. Draw the arcs made with the corners 
of the figure as centers in fine broken lines. 

Draw the center lines in red ink. 




Sheet II. Fig. 11. 

Scale, full size. 

Connecting arcs. 



FIRST DRAWINGS. 149 

T square; triangles; triangular scale; bow pencil and pen; 
compasses; full lines in pencil, full and broken lines in ink. 

Peiicil-tvork. — Center the drawing by diagonals. Find the 
middle points of the half diagonals running N. E. and S. W. 
From the lower one of these centers draw arcs with the follow- 
ing radii: }i" ; /s"; %" \ Yz" ', Va" • 

From the upper one of these centers draw arcs of the fol- 
lowing radii: /s"; %"; W\ %"\ n"- 

Connect the arcs on the lower side, beginning with the 
largest of each set, by arcs with the following radii in succes- 
sion: 2" \ 2^-^"; 2}i" \ 2^^" \ 2y^" . These arcs are convex 
looking from the top down. 

Connect the first set of arcs on the upper side, beginning 
with the largest of each set, by arcs with the following radii in 
succession: 3^"; SyV'^J ZV^" \ 3tV'' 3/^''- These arcs are 
concave looking from the top down. 

The centers of these arcs are found as follows : 

On any line through the center <?', as the line 00' , measure 
off from the arc drawn with o' as a center the distance for the 
radius of the tangent circle. This gives, for instance, the 
point a. On any line through the center o, as the line 00' 
measure off from the arc the same distance, as the point b. 
With 0' as a center and radius o' a^ and with ^ as a center and 
radius ob, strike arcs to meet each other. This is the center 
required, as point e. 

Draftsmen of experience often find these centers by trial, as 
that method is quicker and sufficiently accurate for all practical 
purposes. 

Ink-work. — Draw the larger arcs first with the compasses 
and then the smaller ones with the bow pen. This allows of 
slight bending or springing of the bow pen to allow for 
inaccuracies of the work. 

The lines are made with a fine pen and the two inner sets 
of lines are broken, with dashes about yi" long. Stop the 
inner lines at the points of meeting. 



I50 



MECHANICAL DRAWING. 



The diagonal line used and the construction lines are made 
with red ink. Draw one set of construction lines only as. 
broken lines in red ink. 




Sheet II. Fig. 12. 

Scale, 3" = I foot. 

Extension-bar. 

T square ; triangles ; triangular scale ; compasses ; exten- 
sion-bar; large arcs; pencil and ink; full lines in pencil, full 
and broken lines in ink. 

Pencil-work. — See notes under ' * Compasses ' ' and ' ' Ex- 
tension-bar. " 

Center the figure and draw vertical and horizontal center 
lines. 

From the center of figure measure upwards the following 
dimensions: \%" ; 2^3"; 3^"; A%" \ 5"; 6". 

Find the centers by trial and draw arcs through each of 
these points so that they will pass through the ends of the 
horizontal center line. 

From the center of figure measure downwards the following 
dimensions: i"; i^"; 2^"; 3^^"; 4^"; 6". 

Find centers by trial and draw arcs through each of these 
points so that they will pass through the ends of the horizontal 
center line. 



FIRST DRAWINGS. 



151 



From the center of figure measure to the right the following 



dimensions: li" \ i 



2/8"; 3^"; 4/8''; 5"; 6^ 



Using the following radii in succession, draw arcs through 
the points last marked in succession: 21)^"; 21^-^"; 21^''; 
2 17)3''; 22"; 22^^"; 221^". Extend the lines to the boun- 
daries only. 

From the center of figure measure to the left the following 
dimensions: yi" \ is/g"; 2}4"; 3^"; 4}i" ; 5/''; 6". 

Using the following radii in succession, draw arcs through 
the points last marked in succession: 23^"; 2 ft. ji" ', 2 ft. 
2"; 2 ft. 3}i"; 2 ft. 4j4"; 2 ft. sVa"; 2 ft. ?"■ 

These lines may require the use of the extension-bar. 

Extend the lines to the boundaries only. 

Ink-work. — Ink the first set of lines full with a fair width 
of line. Ink the second set of lines of the same width as the 
first set, but make broken lines with dashes about i^'' long. 
Ink the third and fourth sets of lines in fine full lines. 

Draw the center lines in red ink. 




Sheet II. Fig. 13. 

Scale, full size. 

Ellipses : Irregular curves. 



152 ME CI-IA NIC A L DRA WING. 

T square ; triangles ; triangular scale ; bow pencil and pen ; 
compasses; irregular curves; full lines in pencil and ink. 

Pencil-work. — Center the figure and draw the center lines. 

From the center measure upwards the following dimen- 
sions: %"; %"\ yi"\ I"; i^". 

From the center measure to right or left the following 
dimensions: yi" \ Y^" \ i"; i^"; i^". 

The corresponding horizontal and vertical distances are 
semiaxes of ellipses. Construct the largest three of the ellipses 
on these axes extended to the other side of the center, by the 
following method: 

Draw AB. With (9 as a center swing the distance OB to 
the point D. Take the distance AD and measure it from B 
to C. Bisect AC and extend the bisecting line to meet the 
vertical axis at E. With £ as a center and a radius EB draw 
an arc to right -and left of B, extending it to the line EK. 
With H 2lS z. center draw an arc with HA as a radius ; this line 
will meet the line of the ellipse drawn from B with ^ as a 
center, and this method of construction is an approximate 
method of constructing an ellipse. If the work is not done 
with the utmost accuracy, the irregular curves must be used to 
join the arcs fairly. See note under " Irregular Curves." 

The remaining portions of the ellipse and all parts of the 
other two ellipses are constructed by this method. 

Construct the remaining ellipses by the following method : 
From M lay off the semiminor axis, ON, to the point R. With 
the length RP as a radius describe arcs through N and 5'. 
Make OT =^ i^R- With 7" as a center draw an arc through 
M. If drawn with care this arc meets those already drawn. 

Ink-work. — Draw the arcs of the ellipses first and finish 
with the irregular curves later, if necessary. Care is required 
in carrying the arcs just far enough and not too far. The lines 
are all full lines. 

Draw in red ink the construction lines of one-quarter of 
only one ellipse drawn by each method. Also draw the center 
lines in red ink. 



FIRST DRAWINGS. 



153 




Sheet II. Fig. 14. 

Scale, i^" = I foot. 

Irregular curves. 

T square; triangles; triangular scale; irregular curves; full 
lines in pencil, full and broken lines in ink. 

Pencil-woi'k. — Divide the horizontal center line into twelve 
equal parts, using the triangular scale. 

On the two outside lines next the vertical boundary lines 
measure off from the horizontal center line, above and below, 
the following distances: 6"; j" \ Z" \ g" ; 10"; each measured 
from the center line. 

On the next two interior lines on each side measure off in 
the same way the following distances : 8j^"; 9"; io){" ; 11''; 

113/". 

On the next two lines measure the following distances as 
before: 8/2"; g%" ; io%" ; ii}i"; 12". 

On the next two lines measure the following distances as 
before: 7%"; g" ; 10"; ii"; 11%". 

On the next two lines measure the following distances 
as before: 7%"] Sj4"; g}4" ; 10^''; ii}4". 



154 



ME CHA NIC A L DRA WING. 



On the middle line measure off as before the following dis- 
tances: 7"; ^%"\ 9^2"; \o%"\ ii>^". 

See notes under ' ' Irregular Curves. ' ' 

Through the ends of the horizontal center lines and the 
corresponding measurements draw smooth curves with the aid 
of the irregular curves. Each line is to be tangent to the 
vertical boundary line at the middle points. 

Note that the curves correspond on either side of the center 
lines. 

Ink-work. — Draw the upper lines full lines with a fine pen. 

Draw the lower lines broken lines with the same width of 
pen-opening and dashes about ]/%" long. 

Draw the vertical lines and the horizontal center line in red 
ink. 




Sheet II. Fig. 15. 

Scale, full size. 

Shading fillets. 

T square ; triangles ; triangular scale ; bow pencil and pen ; 
full lines, pencil and ink. 

Pcncil-zvork. — The figure represents a number of blocks 
piled centrally on each other. 



FIRST DRAWINGS. 



155 



Draw the center lines. On one of these Hnes measure from 
the center the following dimensions: /g"; yV'; W '^ ^i'i" \ 

I3V'; 1^8"; ^%"- 

Swing these dimensions around to the other three portions 
of the center lines. Draw squares, using the corresponding 
dimensions. 

Diagonal lines are checks on the accuracy of the work. 

Draw fillets at the corners of all the squares with the fol- 
lowing radii in succession, beginning with the smallest squares: 

3//. 1". j/"' _9_". 5"- 11''- 3/a" 

Ink-work. — Draw the fillets first and complete the squares 
with the rounded corners in full lines with a comparatively fine 
pen. 

Shade the blocks according to the notes under "Shade 
Lines." Draw the center lines and the diagonals in red ink. 

Show in red ink how one of the centers for the fillets is 
found. 




Sheet II. Fig. 16. 

Scale, i" = I foot. 

Shade lines. 



156 



ME CHA NICAL D RA WING. 



T square ; triangles ; triangular scale ; bow pencil and pen ; 
shade lines; full lines in pencil and ink. 

The figure represents blocks resting centrally on each 
other, the smallest on top. 

Pencil-work. — With the center of figure as a center draw 
circles with the following radii: 2" \ y/2'' ; sV^" ', ^" ', n"; 
I4>^"; 18". 

Ink-work. — See notes under "Shade Lines." 

Draw and shade the four outer circles by the first method. 

Draw and shade the three inner circles by the second 
method. 

Draw center lines and diagonals in red ink. 




Sheet II. Fig. 17. 

Scale, i" = I foot. 

Heavy lines with narrow spaces between. 

T square ; triangle ; triangular scale ; bow pencil and pen ; 
compasses ; shade lines ; full lines in pencil and ink. 

The figure represents sections of sheet metal standing on 
end. Where the sheets lap, a fine white line is left, the entire 
width of this being taken from one sheet. The ends of the 
laps are closed, as shown. 



FIRST DRA WINGS. 



157 



Peiicil-zvork. — Use the center of figure as the center for the 
rings of metal. The radii of the mean diameters of the rings 
are as follows : 3"; 6"; 9''; 12^"; 161/^". 

The thicknesses of the sheets, beginning with the outer 
ones, are: i/s"; i" \ Y^" ', %" ; %" . 

Make the joints for the outer rings at the sides and for the 
next inner one at top and bottom. Alternate to the innermost 
one. 

The laps are 30° long, half on each side of the center line. 

Construct the joints of plating. 

Ink-work. — Carefully draw the boundaries of the metals 
with quite a fine opening of pen and fill in with a widely opened 
pen. Do not attempt to bring the heavy ink-lines sharply to 
the ends. Finish them off with the triangle and R. L. pen. 

Draw center lines in red ink. 




Sheet II. Fig. 18. 

Scale, 2" = I foot. 

Shading circles : Hatching. 



T square ; triangles ; triangular scale ; compasses ; bow 
pencil and pen; shading circles; full lines in pencil and ink. 



158 MECHANICAL DRAWING. 

The figure represents a section of a hollow shaft showing 
beyond the section the enlarged portion for the coupling to join 
it to the next shaft. The coupling rests on the rectangular 
block and the shaft is vertical. 

Diameter of the outer circle of the coupling. . . 18" 

Diameter of the outside of the shaft \o" 

Diameter of the axial hole in the shaft 6" 

Diameter of the bolt-circle 14'' 

Diameter of the bolts 2 y[" 

Number of bolts 6 

Pencil-work. — Draw the center lines. The central point 
is the center of the shaft. 

Ink-work. — After the figure is completed, shade the circles. 

Draw the center lines and the bolt-circle in red ink. 

Dimension the drawing in accordance with the notes under 
*' Dimension Lines." Mark the centers of the bolt-holes with 
short full radial lines in red ink. These are at right angles to 
the bolt-circle, thus marking the centers properly. Hatch the 
section. See "Standard Hatching." 

Legend. — The legend is placed in the space left for it and 
is the same as that for the first sheet, except as follows : 

SHEET II. 

CURVED-LINE DRAWING. 

The block lettering is of two types. Curved lines are used 
where possible. 

After the drawing is cut from the board, paper is stretched 
for the next drawing. 



SHEET III. 
WORKING DRAWINGS. 

SKETCHING ; VIEWS ; CENTER LINES ; PROJECTION ; SECTIONS ; HATCH- 
ING ; DIMENSIONS. (see REMARKS UNDER THESE HEADS.) 

Description of Models. — Three brass models are used for 
this sheet. These are cut across in certain planes and the 
parts are pinned together. They may be separated into parts 
in order to study and draw sections. The models are consid- 
ered to be solid and are drawn accordingly. The lines of 
separation are generally along center lines. 

The dowel pins and holes are not drawn. 

The different models of each kind differ slightly in dimen- 
sions, so that care must be taken to note the marks on the 
models used, as it may be necessary to again refer to them after 
the sketches are made. Models are marked on each portion 
with the same characters. Where the portions are of the same 
shape, center-punch marks are placed opposite each other on 
opposite sides of a plane of separation: as, — : — , : : , ; : : , 
etc. 

This conforms to engineering practice. 

GENERAL DIRECTIONS FOR WORK. 

Stretch paper for this sheet. 

The drawings of the views are to " Scale, full size." 
The sheet is to be inked and completed, not traced. 
Sketch model I. 

Inspection of sketch. 

Pencil the views of model I on drawing-paper. 

159 



l6o MECHANICAL DBA WING. 

Inspection. 

Cover drawing with paper. 
Same, model II. 
Same, model III. 
Pencil legend. 
Inspection. 
Ink and completely finish the views of model I. 

Inspection. 

Cover drawing with paper. 
Same, model II. 
Same, model III. 

Ink legend, draw border, clean drawing. 
Inspection. 
Cut drawing from board. 

GENERAL DESCRIPTION OF SKETCHING. 

Sketches of the different views of each model are first made 
in the sketch-books. Note carefully that no instruments but 
the medium hard lead-pencil are used in making the sketches. 
Even the center lines and the arcs must be drawn free-hand. 

Only the foot rule and the calipers are used in making the 
measurements. 

Unless the model is large, it is best to make the sketches 
of such a size that they will all go on one page or two facing 
pages of the sketch-book. The different views must be pro- 
portioned in size to the real sizes of the views of the models. 

As the number of views and sections required for this sheet 
are given, decide for each model whether to make them of a 
size that will fit on one or two pages and thus decide approxi- 
mately how large each view must be sketched and the position 
it will occupy in the sketch-book. 

Always fix the positions of the Plan, Front Elevation, and 
Side Elevation first and draw them first. Later on, place the 
sections where most convenient. If the book is large enough 



FIJ^ST DRA WINGS. l6r 

to place the sections so that they may be partly projected from 
one of the other views, it is Avell to arrange the positions of the 
sections accordingly. Generally, however, sections are placed 
in any convenient position after the main views are drawn. 

It is generally best to draw the Plan first and project from 
that for the Front Elevation, but it must be decided upon in 
each case. 

First draw the vertical center line for the Plan and Front 
Elevation. Then decide on the position of and draw horizontal 
center lines for the Plan and for the Front and Side Elevations, 
if the views are symmetrical about centers. Next draw a ver- 
tical center line for the Side Elevation. This establishes the 
positions of the central points of the views, if symmetrical. If 
the views are not symmetrical, decide on whatever center lines 
there are and draw them. 

After deciding on the view to be sketched first, place the 
object or yourself in such a position that the face that is to be 
sketched of the model is normal to the line of sight. Draw 
the principal boundaries first, if the figure is symmetrical care- 
fully making the corresponding boundaries equally distant from 
the center line. Draw all lines that appear to view first and 
later put in the hidden lines as broken lines. 

After the first sketch is completed, draw next the one that 
seems most easily sketched and measured. Each correspond- 
ing point and line must be projected vertically or horizontally. 

After the Plan, Front Elevation, and Side Elevation are 
sketched, place all the necessary dimension extension lines; 
then the arrows ; then the dimension lines. Measure the model 
and place the dimensions in the spaces left. Place each 
dimension once only on the views, but choose a position for it 
that will show it clearly. 

Mark where advisable on these view^s in heavy broken lines 
the positions of the planes where the sections are to be taken ;, 
mark the ends of these broken lines; A- - - -B, C- - - -D, 
etc. 



l62 MECHANICAL DRAWING. 

After the three views are dimensioned, separate the model 
.at the plane where a section is to be made and place the sec- 
tion normal to the line of sight. Either portion may be drawn 
as desired, but one is generally more important on account of 
the part of the model beyond the section plane. Note that 
part of the figure is removed entirely, and the part remaining 
only is drawn and the surfaces cut by the plane hatched. 

Choose a position in the sketch-book, if there be space, so 
that as many points as possible may be projected from a view 
already drawn ; if the size of the book and the other sketches 
do not allow of this, place the section wherever convenient and 
sketch the portion of the model remaining as if it were a new 
model, making the sketch as near the size of the corresponding 
view already drawn as possible. Draw the vertical center line 
and any other center lines first. As before, draw all lines that 
appear to the eye first and later the hidden lines. Note that 
all the lines beyond the section plane must be drawn. When 
completed, hatch rapidly, free-hand, either a portion or all of 
each surface cut by the plane, using the proper Standard Hatch- 
ing. Hatch enough to clearly indicate what metal is used and 
how far the surfaces extend. 

Mark the section sketched, Section on , to agree, 

with the letters placed on one of the other views to show where 
the section is taken. 

Make sketches of all the required sections. 

It is seldom, except in very complicated drawings, that 
many dimensions are placed on a section. It is never done if 
the dimensions may be conveniently placed on the other views. 

Over the sketches for this sheet only place the names of the 
views sketched and draw projection lines for every point or 
surface projected. 

The projection lines are short dashes and extend for only 
a distance of y^^" to ^s" away from the point or surface pro- 
jected and the same distance back from the position projected 
to. 



FIRST DRA WINGS. 1 63 

When all the sketches of each model are completed, they 
are inspected before the drawing is begun. 

GENERAL DIRECTIONS FOR DRAWING SHEET III. 

Working line 1 5 " X 2 1 '' 

Border line 16" X 22" 

Cutting line 18" X 24" 

The legend is placed in the lower right-hand portion, as 
usual, and is as follows: 

Sheet III, [Block lettering of simple type.] 
WORKING DRAWINGS. [Free-hand lettering, large.] 
Sketching; Views; Center lines; Projection; Sections; Hatching; 
Dimensions. [Free-hand lettering, small.] 

Sketched and drawn from brass models. 

Scale. [Free-hand lettering, small.] 

Name. [Autograph.] Date. [Free-hand lettering, small.] Class. [Same.] 

On this sheet only place the names of the views over them 
in free-hand lettering. 

When sections are made, place above the views in free- 
hand lettering, Section on , using the same letters that 

mark the section plane in one of the views. This applies to 
all drawings. 

On this sheet only draw projection lines for every point pro- 
jected. The projection lines are not made of dots, but of very 
short dashes. They extend for only a distance of }{" to Y^" 
away from the point projected and the same distance back from 
the position projected to. They are drawn in red ink. 

Make the pencil-lines full and broken lines as required. 

Do no hatching in pencil. 

Draw no projection lines in pencil. 

Place no dimensions in pencil. 

Ink-work. — Carry out the established method of drawing 
all vertical lines first, full and broken, and then sweep down 
the board with the T square for all horizontal lines wherever 
found. 



1 64 ME CHA NICAL DRA WING. 

When the shade Hnes are drawn, set the pen to proper 
width and never change the setting while drawing the shade 
lines. 

Carry out the ' ' Plan of Procedure ' ' for inking. 

Note carefully which lines are to be drawn broken and 
which surfaces hatched. The sketches should be so complete 
in these details that ihey may be followed absolutely in inking 
the drawing. 

POSITIONS OF THE VIEWS ON THE SHEET. 

A distance of }^" separates horizontally all views of the 
same model. The vertical distances between the views are 
given for each model. 

Place the views of model I as follows: 
Section on CD. 
Plan. 

Front Elevation. Side Elevation. 
Section on AB. Section on EF. 
The views to the left touch the left hand, top, and bottom 
working lines. The vertical distances between the views are 
equal. 

In the space to the right of " Section on CD " is placed: 

Model I. 

GUIDE-BLOCK. 

Place the views of model II as follows: 

Plan 

Side Elevation, half section on CD. Front Elevation. 

Section on AB. 

The vertical center line of the Plan is on the vertical center 
line of the sheet. The top of the Plan touches the top working 
edge. A vertical distance of iYt," separates the views in the 
same vertical line. 

In the space below " Section on AB " and centrally under 
it is placed: 



FIRST DRAWINGS. 165 

Model II. 

BOTTOM JOURNAL BRASS. 

Place the views of model III as follows: 

Plan. 

Front Elevation. Side Elevation, half section on AB. 

Section on CD. 

The " Side Elevation, half section " touches the right-hand 
working line. 

A vertical distance of ^'' separates the views in the same 
vertical line. 

In the space to the right of the Plan is placed : 

Model III. 

CROSS-HEAD. 



MODEL I. 



Make a working drawing of the model of a guide-block. 

Three views. Plan; Front Elevation ; Side Elevation: and 
sections through the horizontal center line of the Plan ; the 
vertical center line of the Front Elevation ; and through a hori- 
zontal plane about ^ " below the top of the Front Elevation. 

The figure represents a block of cast iron which is bolted 
to the framing of an engine by bolts passing through holes (not 
shown) extending vertically through at the points marked for 
the centers of the curves of the corners. The rectangular 
depression acts as a guide to a rectangular rod moving back 
and forth longitudinally. 

The moving rod is horizontal, therefore the Plan will be 
the view looking down on the model placed so that the 
depressed portion is seen from above. 

Sketching. — Draw the vertical center line for the Plan and 
Front Elevation; horizontal center line for the Plan; horizon- 
tal center line for the Front and Side Elevations ; and vertical 
center line for the Side Elevation. 

Sketch the Plan. Project downwards from each vertical 



i66 



MECHANICAL DRA WING. 



line of the Plan a series of short dashes. These define the 
limits of the horizontal lines in the Front Elevation. Sketch 
the Front Elevation, using these projection lines for limits for 
the horizontal lines. The lengths of the vertical lines are 
decided by eye, noting that the boundaries of the view are 
equally distant from the horizontal center line. Note the 




FIRST DRA WINGS. 



167 



hidden lines showing that the depressions on the vertical side 
boundaries of the Plan appear as vertical lines in the Front 
Elevation. These are projected from the Plan, or the surface 
a projects to ad'. 

Draw projection lines horizontally from all horizontal lines 
of the Front Elevation. These define the limits of the vertical 
lines of the Side Elevation. 

Sketch the Side Elevation, using the projection lines from 
the Front Elevation as limits for the vertical lines. The 
lengths of the horizontal lines are determined by eye, noting 
that the boundaries of the views are equally distant from the 
vertical center line, and that the horizontal lengths of this view 
should agree with the vertical heights of the corresponding 
lengths in the Plan. Note that the bottom of the depression 
in the Front Elevation becomes a hidden line in the Side 
Elevation, the line extending across the view. 

Dimensions. — Place arrows, as shown, for measurements 
and draw dimension extension and dimension lines. The radii 
of the arcs in the Plan must be given and the positions of the 
centers. Note that no dimensions are required for the Side 
Elevation, dimensions in the vertical direction being given in 
the Front Elevation and in the horizontal direction in the Plan. 

The sketches are now complete as far as the main views 
are concerned. 

/Otde. t i^.v Coil- <i7-^^ 





L — - -•; 






" 


" 


— — 


1 





i68 



MECHANICAL DRAWING. 



Sections. — Sections are required on planes AB^ CD, and 
EF. Mark these planes on the proper views with heavy 
broken lines and letter them, as shown. 

As stated, place these views in the sketch-books to best 
advantage. 

Section on AB. — Divide the model on the line AB and 
sketch one portion, looking towards the surface cut by the 




plane. The position with reference to the model is the same 
as when the Front Elevation was sketched. 

Sketch the model as it appears. 

Note that the outer boundary is the same as that of the 
Front Elevation. Part of the view could, then, be readily 
projected from the Front Elevation. 

Hatch the surface cut by the plane. Use the Standard 
Hatching for cast iron. Mark the sketch, " Section on AB." 

Sectio7i on CD. — Join the portions of the model and divide 
it on the plane CD. Sketch the larger portion, looking 
towards the surface cut by the plane. The position with refer- 
ence to the model is the same as when the Plan was drawn. 

Sketch the model as it appears. It is exactly the Plan 
repeated, except that the side portions are hatched where cut 
by the plane. Part of the sketch could be readily projected if 
placed at the top or side of the Plan. 



FIRST DRA WINGS. 



169 




Section on EF. — Join the portions of the model and divide 
again on the plane EF. 

Sketch one portion, looking towards the surface cut by the 




plane. The position is the same as when the Side Elevation 
was drawn. 

Sketch the model as it appears and hatch the surface cut 
by the plane. 



1 70 ME CHA NICA L D KA WING. 

Note that the lines showing the intersections of the curved 
corners with the side boundaries in the middle of the height 
become vertical broken lines. 

Part of the sketch could be projected from the Side Eleva- 
tion and the rest from the Front Elevation. 

Mark the sketch, " Section on EF.'" 

Below the sketches and in the lower right-hand corner of 
the page, write : 

Model I. Guide-block. 

DIRECTIONS FOR DRAWING MODEL I. 

Pciicil-zvork. — After centering the paper and drawing the 
three dimension lines of the sheet, note that the views to the 
left of model I touch the left-hand and the top and bottom 
working lines. 

From the sketches, decide on the position of the vertical 
center line of the left-hand views and draw it vertically the 
whole length of the working line. 

From the sketches, decide on the total vertical distance 
remaining for spaces between the views and divide this distance 
equally for the spaces. 

Draw the extreme horizontal bounding lines of the views 
and their horizontal center lines. Check to see that there is 
the same distance between the views. 

Plan. — Draw the Plan first. Measure when possible from 
the center lines half the dimensions on either side. Make as 
few measurements as possible. Measure once and project up 
and down or sideways for corresponding points. Fix the 
center of one of the bolt-holes and project in directions at right 
angles. Fix the center of the diagonally opposite one and 
again project in directions at right angles. This establishes 
the four centers. 

Front Elevation. — Project vertically downward from the 
Plan the lines of the vertical surfaces and draw them across the 
view of the Front Elevation. Only one measurement is made 



FIRST DRAWINGS. I /I 

— that for the depth of the depression in the model. Draw the 
hidden lines, projecting properly. 

Carefully mark on the Plan and Front Elevation the posi- 
tions of the planes where sections are to be taken. 

Side Elei'ation. — Project horizontally from the Front Eleva- 
tion, noting that the bottom of the depression in the model 
becomes a broken line. The horizontal distances need not be 
measured ; they may be taken with the dividers from the ver- 
tical distances on the Plan. 

Section on AB. — Project downward from the Front Eleva- 
tion. The vertical dimensions may be taken from the Front 
Elevation by dividers. 

Sectio7i on CD. — Project upwards from the Plan and make 
the view the same as the Plan, as in the sketch. 

Section on EF. — Project horizontally from ' ' Section on 
AB'' and downwards from the Side Elevation. The view is 
entirely finished from these projections. 

Note the part to be hatched. 

Ink according to directions. 

MODEL II. 

Make a working drawing of a model of a Bottom Journal 
Brass. Metal: composition. Three views: Plan; Front Eleva- 
tion; Side Elevation, half in section; and a section through 
the horizontal center line of the Plan. Scale, full size. 

The model represents the lower half of a pair of ' ' Brasses ' ' 
in which a shaft revolves. It is made "flat sided" on the 
under side to prevent its turning in the framing in which it 
rests. 

As it is the lower "brass," the Plan is the view looking 
into the concave surface. 

In this case, in order to fit better on the drawing-paper, 
the Side Elevation is taken to the left. 

Sketching. — It will be found best to sketch the Front 
Elevation first, as one measurement only is required for the 



172 



MECHANICAL DRAWING. 



diameters of the half circles shown on the Front Elevation, and 
the radii used will define both ends of the diameters, which 
may be projected vertically to the Plan. The basis of work in 
this view is, then, the top line of the brass. 

Note also that the shape of the " flat-sided " portion of the 
bottom of the "brass " is drawn in the Front Elevation and 
the edges projected to the Plan. 

There are many more hidden lines than in the views of 
model I; all must be carefully drawn. 

Draw the vertical center line for the Plan and Front Eleva- 
tion. Leave space above for the Plan and sketch the Front 
Elevation. Project upv/ards and sketch the Plan. 

Carefully mark the positions of the planes where sections 
are to be taken. 

The Side Elevation is projected to the right or left of the 
Front Elevation. Dra*v a vertical center line for this view at 
the proper distance away from the Front Elevation. Sketch 
half of this view only — the portion to the right or left of the 
vertical center line. 







To finish the Side Elevation, half in section, separate the 
model on the plane CD and hold the half that is used in the 



FIRST DRAWINGS. 



173 



same position as when sketching the Side Elevation. Sketch 
half of the half model, placing proper Standard Hatching on 
the surface cut by the plane. 

Note that the outline is the same as for the rest of the view, 
the difference being in the lines seen and hidden. 

The vertical line separating the elevation from the section 




174 



MECHANICAL DRA WING. 



is a full line. The center line continues beyond above and 

below. 

Mark the view, Side Elevation. " Half section on CD.'" 
Dimensions. — Place arrows, lines, etc., for measurements, 

as shown. Note that all the measurements are on the Plan 

and Front Elevation. All arcs are dimensioned by diameters 

where possible. 

Section on AB. — Unite the parts of the model and separate 

again on the plane AB. Place the half model so that the sur- 



\)jU<L/t 



7^ ^3 




face cut by the plane is at right angles to the line of sight and 
sketch it. 

Note that the model is now in the same position as when 
the Front Elevation was drawn, and that the boundary is the 
same. Hence this view might be largely projected from the 
Front Elevation. 

Hatch the surface cut by the plane. Note carefully the 
hidden lines. 

This sketch is placed so it may be projected, if possible. 

Mark the sketch, "Section on AB.'' 

Mark the sketches, " Model H. Bottom Journal Brass." 



FIRST DRAWINGS. 1/5 

DIRECTIONS FOR DRAWING MODEL II. 

Draw the vertical center line for the Plan, Front Elevation, 
and Section on AB, and the horizontal center line for the Plan. 

Draw the horizontal boundary lines for the Plan and the 
top line of the Front Elevation. On this last line measure from 
the vertical center line, the radii of the arcs having this point 
for a center, and draw the arcs ; the distances for the vertical 
parts of the " flat-sided " portions of the base and draw vertical 
lines; and the half extreme horizontal dimensions of the 
"brass " and draw vertical lines. Measure from the top line 
down the vertical center line for the position of the center of 
the lower bounding arc and with the proper radius draw the 
arc. This arc should join tangentially the vertical lines for the 
outer vertical boundaries. Measure downward from the same 
point for the position of the bottom of the " flat-sided " portion 
of the base of the ' ' brass ' ' and for the depth of the vertical 
flat portion on the two sides. Draw an indefinite line for the 
bottom flat and measure along it the half widths. This defines 
the bottom edges. Project across from the measurements 
taken for the ends of the vertical ' ' flat-sided ' ' portions. Con- 
nect the two sets of points last found on the two sides. The 
lines connecting the portions of the under part are thus deter- 
mined. 

Project upwards for the Plan. All the necessary measure- 
ments are made on the vertical center line, and the horizontal 
lines are drawn in the proper places from these measurements. 
In this case, all the lines cross the figure to their respective 
boundaries, which are projected upwards from the Front Eleva- 
tion. The radii of the curves at the corners are not important, 
but the approximate radii found for the sketches are used. 
The radii are about ^i" . 

Draw the vertical center line for the Side Elevation, half in 
section. 

Project to the left from the Front Elevation for the horizon- 



1/6 MECHANICAL DRAWING. 

tal lines. The horizontal dimensions are obtained from the 
vertical heights of the Plan. Measure always from the vertical 
center line. Note that the lines are the same for both parts of 
the view in the pencil-work, some full, some broken. 

Section on AB. — As this is simply a copy of the Front 
Elevation with a variation in the lines made full or broken, 
project down from the Front Elevation and take the vertical 
measurements from it with the dividers. Lay these measure- 
ments off on the vertical center line as usual and project across. 

Ink according to directions. 

MODEL III. 

Make a working drawing of a model of a cast-steel Cross- 
head for a small horizontal engine. Three views : Plan ; Front 
Elevation ; Side Elevation, half in section ; and a section 
through the horizontal center line of the Plan. Scale, full size. 

The figure represents the sliding-block of metal that con- 
nects the reciprocating or " back-and-forth " motion of the 
piston and piston-rod in the cylinder with the rotary motion of 
the crank and the shaft. As the engine is horizontal, the 
broad, flat portion is below and furnishes a large surface for 
support as the Cross-head moves back and forth on the guide. 
Therefore, the Plan view is the one where the flat portion is 
downwards. 

The two cylindrical portions show where the forked "con- 
necting-rod," that connects the, cross-head and the crank-pin, 
grasps the cross-head. These are called journals. The 
piston-rod is secured through the middle of the square-faced 
portion between the cylindrical pins. The hole for this is not 
shown. The projection on the side of the cross-head is for the 
purpose of securing there a horizontal pump-rod which moves 
with the cross-head. The center of the hole for the rod is in- 
dicated. 

Sketching. — In this case the figure is generally symmetrical 
in the Plan view, but not so much so in the other views; so the 



FIRST DRAWINGS. 



177 











178 MECHANICAL DRAWING. 

vertical center line for the Plan and Front Elevation is drawn 
and the horizontal center line for the Plan, but no horizontal 
center line for the Front Elevation and Side Elevation. The 
vertical center line for the Side Elevation may now be drawn, 
but it is better to wait until the Front Elevation is completed. 
Also, it may be readily seen that it is better to sketch the Front 
Elevation first, as it gives a better view and a better under- 
standing of the model. 

Leave room for the Plan above. Draw a center line for the 
two cylindrical portions, or journals, and extend this for the 
Side Elevation. Sketch the Front Elevation and project for 
the Side Elevation and Plan. Mark the views properly. Note 
carefully what lines of the Plan are concealed by the projecting 
portions above. 

For the half-section on AB separate the model on that 
plane and place it normal to the line of sight and sketch it. 
The outline corresponds with that of the Side Elevation, as the 
part remaining beyond the section is a fac-simile of the part 
already sketched. 

Note that the circle seen by looking at the end of the 
journal becomes a broken line in the section, as the nearer 
cylinder is removed and the farther one is hidden. Note also 
that the lines defining the outline of the portion for securing the 
pump-rod are now gone, as all this portion is removed. 

Mark the sketch, " Side Elevation, half-section on AB." 

Dimensions. — Place arrows, etc., as shown. The dimen- 
sions are again placed on the Plan and Front Elevation only. 
The approximate shapes of the arcs defining the outlines are 
determined after the drawing is made on the drawing-board, 
as they are simply clean arcs joining the determined points. 
The positions of the beginning and ending of these arcs must 
be accurately determined and noted on the sketches. The 
center of the pump-rod is the center of the arc around the 
metal at that place and is accurately shown, as well as the 
radius of the curve. 



FIKST DKA WINGS. 



179 



Section on CD. — Separate the model on the plane. 
Place the sketch as advisable in the sketch-book, noting 
that portions of it may be projected from any of the other views. 




It is seen that the outline exactly corresponds with that of the 
Front Elevation and that the entire surface is hatched. Care- 
fully draw all broken lines representing hidden lines beyond 
the section. 

Mark the sketch, " Section on CD.'' 

Mark the set of sketches, 



Model III. 

C ROS S-HE AD. 
DIRECTIONS FOR DRAWING MODEL III. 
Lay off along the top working line from the upper right- 
hand corner the distance of the half width of the Side Elevation 
and draw a vertical center line of indefinite length for the 
center line of the Side Elevation. 

From the sketches, determine the distance between this 



l80 MECHANICAL DRAWING. 

center line and the one through the Plan, Front Elevation, and 
Section on CD, allowing the proper distance between the views, 
and draw the new center line. Lay off downward on this 
center line from the top working line the half height of the Plan 
view and draw the horizontal center line for the Plan. Draw 
the boundaries of the base in the Plan. 

From the lower boundary of the Plan lay off the proper 
amount for the vertical distance between the views and draw 
the top line of the Front Elevation. Next draw the center 
line for the journals and continue to draw the figure from the 
dimensions of the sketches, measuring always along center lines 
when possible. 

After completing the Front Elevation, project for the hori- 
zontal lines of the Side Elevation and the vertical lines of the 
Plan. Either Plan or Side Elevation maybe finished first; but 
it is easier to draw the Side Elevation using the dimensions 
given on the Plan sketch, and then take these dimensions with 
the dividers from the Side Elevation and use them in drawing 
the Plan. 

The curved lines for the boundaries of the curved surfaces 
extending from the upper to the lower parts of the Front and 
Side Elevations are not necessarily arcs of circles, but are 
generally drawn as such, as the pattern-maker does not require 
accurate curves and will fashion them as required when he 
makes the pattern for casting. The arcs are drawn tangent at 
points a (see sketch) and of radii such that the lower portions 
of the arcs reach the points b. These radii and the positions 
of the centers on the horizontal line through aa are found by 
trial. In the Plan, the corresponding curves are approximated 
to in the same manner. These may be drawn with irregular 
curves as guides. 

The curve in the Front Elevation defining the boundary of 
the surface extending down to the side extension for the pump- 
rod is drawn as an arc of a circle with its center on the line aa 
and a radius and position of center (found by trial) to cause the 



FIRST DRAWINGS. l8l 

arc to join at a tangent the arc drawn from the center of the 
hole for the pump-rod. 

Half- section on AB. — This corresponds with portions of the 
Side Elevation, as shown in the sketch, and is drawn at the 
same time as the Side Elevation. 

Section on CD. — This is a reproduction of the outlines of 
the Front Elevation, so that vertical projections define all hori- 
zontal lengths and the vertical distances are taken from the 
Front Elevation with the dividers. 

Carefully draw the horizontal center line first. 

Ink accordinsf to directions. 



Legend. — In inking the legend, use as little time as possible. 
Do not make the block letters solid unless they are sufficiently 
narrow so that a stroke of the R. L. pen will suffice. 

Make the border simple and make the right-hand and 
bottom lines heavier than the others. The widths of the parts 
of the border line should be in accord with the rest of the 
drawing. 

When cleaned and inspected, cut the drawing from the 
board. 



1 82 



MECHANICAL DRAWING. 



STANDARD DIMENSIONS OF BOLTS AND NUTS FOR THE 
UNITED STATES NAVY. 



Diameter. 


Area. 


Threads. 


Long Diameter. 


Short D. 


Depth. 


Col. I. 


Column 2. 


Column 3. 


Column 4. 


Column 5. 


Column 6. 


Column 7. 


Column 8. 


Col. 9. 


Nom. 


E«. 


Eff. 


No. 


Hex. 


Sq. 


W. 


Head. 


Nut. 


I 


.185 


.026 


20 


9 


23 

a 2 


h 


i 


i 


J% 


.240 


• 045 


18 


1 1 
Is 


2 7 
3? 


19 
3 2 


if 


T^ff 


1 


.294 


.067 


16 


25 
3 '2 


31 


11 


H 


f 


l\ 


•345 


-093 


14 


29 
3^ 


lA 


26 
3^ 


2D 
6T 


7 


k 


.400 


.125 


13 


I 


li 


7 


7 


1 


1% 


•454 


.162 


12 


li 


If 


li 


31 


9 


1 


•507 


.202 


II 


lA 


li 


iiV 


1 7 
3^ 


1 


s 

4r 


.620 


.302 


10 


lA 


If 


li 




3 


i 


•731 


.419 


9 


If* 


25V 


lA 


II 


7 

S 




■837 


•550 


8 


i| 


2^ 


If 


if 


I 


li 


.940 


.694 


7 


2/^ 


2A 


ifl 


If 


li 


lir 


1.065 


.891 


7 


2A 


^3^ 


2 


I 


li 


If 


1. 160 


1-057 


6 


^3^ 


33^ 


2A 


1/2 


If 


4 


1.284 


1.294 


6 


2f 


-,11 

33^ 


2| 


It\ 


a 


If 


1.389 


1.515 


5* 


2|i 


3l 


2t^ 


lA 


i| 


t8 


1.491 


1.746 


5 


3A 


3l 


2i 


If 


If 


T 7 


1. 616 


2.051 


5 


3M 


43'^ 


2lf 


I?? 


If 


2 


1. 712 


2.302 


4i 


3if 


4il 


3i 


lA 


2 


2i 


1.962 


3.023 


4i 


4A 


4tI 


3^ 


If 


2i 


2i 


2.176 


3-719 


4 


4M 


Sal 


3| 


lif 


2i 


2| 


2.426 


4.622 


4 


4|| 


6 


4i 


2| 


2| 


3 


2.676 


5.624 


4 


ell 
5 3 "J 


6il 


4f 


2A 


3 


3i 


2.926 


6.724 


4 


r25 


7tV 


5 


2i 


3i 


3i 


3-176 


7.922 


4 


6A 


111 


51 


2H 


3i 


3l 


3.426 


9.219 


4 


6f 


81 


5i 


2| 


3f 


4 


3.676 


10.613 


4 


7t^. 


sfi 


H 


3tV 


4 


4ir 


3.926 


12. 106 


4 


7i 


9t\ 


6i 


3i 


41- 


4i 


4.176 


13.697 


4 


7if 


9|f 


6| 


3tV 


4^ 


4l 


4.426 


15-386 


4 


81 


lOi 


7J 


3f 


4f 


5 


4.676 


17-173 


4 


81§ 


lofl 


7i 


3ll 


5 


Si 


4.926 


19.058 


4 


9i 


"A 


8 


4 


Si- 


5i 


5-176 


21.042 


4 


9i^ 


"li 


8f 


4A 


Si 


5l 


5-426 


23.123 


4 


iOs% 


I2f 


8f 


41 


5f 


6 


5.676 


25.303 


4 


loH 


I2|| 


9i 


4^ 


6 



STANDARD HATCHING. 




CAST IRON. 




NICKEL STEEL.J 






;mickelsteeu 
' harv-eyed. 








CAST STEEL. 



BRASS OR 
COMPOSITION. 




VULCANITE. 





WRO'T STEEL. 




COPPER. 







GLASS. 



BRICK. 



WOOD. 





CEMENT. 




ALUMINUM. 



183 



SPECIAL METHODS OF THE BUREAU OF ORD- 
NANCE, NAVY DEPARTMENT. 

All lines are in black ink. 

Center lines: 



One long and two short dashes, slightly heavier than 
dimension lines. 
Section planes : 

Same as center lines. 
Dimension lines : 

One long and one short dash. 
Imaginary positions indicated by: 

Long dashes. 
Hidden lines : 

Short dashes. 

Dimensions are in decimals for special ordnance work. 

Special scales are generally used, but the one decimal 
scale on the triangular scale may answer if calculations are 
made at the same time. 

184 



SPECIAL METHODS OF THE BUREAU OF CON- 
STRUCTION, NAVY DEPARTMENT. 

All lines are in black ink. 

Center lines and dimension lines: 

One long and one short dash. 

185 



INDEX. 



Arrows, 60 

Beam-compasses, 29 

Block letters, 78 to 82 

Blue-printing, 98 

Bolts and nuts, 70 

Bolts and nuts, standard, 182 

Border line, 75 

Bow spacers, 22, 124, 137 

Bow pencil, 22, 135, 136, 137 

Bow pen, 22, 135, 136, 137 

Breaks, 56 

Brushes, 29 

Bureau of Construction, 185 

Bureau of Ordnance, 184 

Calipers, 30 
Center Lines, i, 41 
Centers, horn, 28 
Compass, beam, 22, 29 
Compasses, 19, 133, 135 
Compasses, test, 20 
Compasses, use, 20 
Cone, line shade, 89 
Construction Bureau, 185 
Curves, irregular, 25 
Cutting line, 75 
Cylinder, line shade, 86 

Dimension extension lines, 57, 126 
Dimension lines, 57, 126 
Dimensions, 167, 174, 178 
Dimensions, figures, 61, 126 
Dimensions, figures, decimal, 61 
Dimensions over all, 59 
Dividers, 24 
Dividers, use, 24 
Dividing lines into parts, 125 
Drawing-board, i 

Ellipses, 151 
Erasers, 27 



Erasers, rubber, 27 
Erasers, metal, 27 
Erasing shields, 28 
Extension-bar, 21, 150 

File, 4 

Fillets, 47, 138, 154 
First drawings, 106 
Flat tint, 93 

General Arrangement, 34 

General Remarks, 105 

General View, Sheets I and II, 106 

Hatching, 51, 128, 157 
Hatching, standard, 183 
Horizontal lines, i, 7 
Horn centers, 28 

Ink, black, China, 5 
bottled, 5 
red, 5 
Irregular curves, 24, 151, 153 
Isinglass, 29 

Jam-nuts, 74 

Leads, 2 

Lead, sharpening, 3 

Lead-wire, 31 

Legend, 76, 132, 158, 181 

Lettering, 76 

Lettering, free-hand, 83, 84 

Letters, block, 28, 79 to 82 

Light, 2 

Lines, 2, 3, 40 

border, 75 

center, 41 

cutting, 75 

dimension, 58 

extension, 58 

shade, 43, 155, 157 



187 



188 



INDEX. 



Lines, shade, bolt-heads, 49 

sections, shafts, etc, 49 
working, 75 
Line shading, 85, 129 
cone, 89 
cylinder, 86 

hollow, 89 
sphere, 90 

Marking dimensions, 5 
Models, 159 
Model I, 165 
11. 171 

in, 176 

Nuts, 70 

jam, 74 

Ordnance Bureau, methods of, 184 

Pads, for sharpening leads, 5 
Paper-cutters, 31 
Paper, stretching, 32 
Parallel lines, to draw, 8 
Pen, right-line, 13 
Pencils and pencilling, 2 

Artist, 3 

points, 3 

sharpening, 3 

compasses, 3 
Pencil, use of, 5 
Pencilling drawings, 103 
Plan of procedure in making a 

drawing, 102 
Plan of procedure in inking a draw- 
ing, 104 
Pricker, 5, 29 
Profile drawings, 34 
Projections, 38 
Protractors, 26, 130, 145 

Right-line pen, 13 

clean, use, etc., 13-18 
Rule, foot, 30 

Scales, 10 to 12, 76, 83 
Screw-threads, 62 



Secure paper on board, 2 

tracing-cloth on board, 2 
Sections, 50, 128, 168, 174, 179 
Shade lines, 43 to 49, 155, 157 
Sheet I, 107 

n, 133 

HI, 159 
Shields, erasing, 28 
Sketches, 99, 160, 165, 171, 176 
Spacers, bow, 22 
Sphere, line shade, 90 
Splines, 31 
Standard bolts and nuts, 182 

hatching, 183 
Stippling, 95 

Tails, 74 
Thumb-tacks, 2 
Threads, double, etc., 68 
screw, 62 
square, 67 
Tint, fiat, 93 
Tinting, 85 to 92 
cone, 96 
cylinder, 96 
sphere, 97 
Tracings, 35, 95 
Trams, 29 
Triangles, 8 

test, 9 

45°, 114, 115, 119, 120, 121 
60°, 116, 117, 120 to 122 
Triangular scale, 10 

use, 13 
guard, 13 
Truing up, i 
T square, 6 

Vertical lines, i, 7 
Views, 36 

Weights, 7 

Wire, lead, 31 

Working drawings, 35, 159 

business method, 35 
Working-edge, i 
Working line, 75 



SHORT-TITLE CATALOGUE 

OF THE 

PUBLICATIONS 

OF 

JOHN WILEY & SONS, 

New York. 
London: CHAPMAl^ & HALL, Limited. 



ARRANGED UNDER SUBJECTS. 



Descriptive circulars sent on application. 

Books marked with an asterisk are sold at net prices only. 

All books are bound in cloth unless otherwise stated. 



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Armsby's Manual of Cattle Feeding 12mo, $1 75 

Downing's Fruit and Fruit Trees 8vo, 5 00 

Grotenfell's The Principles of Modern Dairy Practice. (Woll.) 

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Kemp's Landscape Gardening 12mo 

Mayuard's Landscape Gardening IShio 

Steel's Treatise on the Diseases of the Dog 8vo 

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Woll's Handbook for Farmers and Dairymen 12mO; 



2 00 

2 50 

1 50 

3 50 

2 50 
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" Architectural Iron and Steel 8vo, 3 50 

" Compound Riveted Girders 8vo, 2 00 

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2 



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Young's Simple Elements of Navigation. 16mo, morocco, 2 00 

first edition 1 00 

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Thurston's Alloys, Brasses, and Bronzes Svo, 2 50 

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ASTRONOMY. 

Craig's Azimuth 4to, 3 50 

Doolittle's Practical Astronomy Svo, 4 00 

<jrore's Elements of Geodesy Svo, 2 50 

Hayford's Text-book of Geodetic Astronomy Svo. 8 00 

* Michie and Harlow's Practical Astronomy Svo, 3 00 

♦White's Theoretical and Descriptive Astronomy 12mo, 2 00 

BOTANY. 

Baldwin's Orchids of New England Small Svo, 1 50 

'Thome's Structural Botany 16mo, 2 25 

'Westermaier's General Botany. (Schneider.) Svo, 2 00 



BRIDGES, ROOFS, Etc. 

{See also Engineeiung, p. 7.) 

Boiler's Highway Bridges 8vo, $2 OO' 

* " The Tbames River Bridge 4to, paper, 5 00' 

Burr's Stresses in Bridges 8vo, 3 50' 

Crehore's Mechanics of the Girder 8vo, 5 00 

Du Bois's Stresses in Framed Structures Small 4to, 10 00 

Foster's Wooden Trestle Bridges 4to, 5 00 

Greene's Arches in "Wood, etc 8vo, 2 50 

" Bridge Trusses 8vo, 2 50' 

" Roof Trusses 8vo, 1 25 

Howe's Treatise on Arches 8vo, 4 00 

Johnson's Modern Framed Structures Small 4to, 10 00 

Merrimau & Jacoby's Text-book of Roofs and Bridges. 

Part I., Stresses 8vo, 2 50' 

Merriman & Jacoby's Text-book of Roofs and Bridges. 

Part n.. Graphic Statics 8vo, 2 50' 

Merrimau & Jacoby's Text-book of Roofs and Bridges. 

Part ni., Bridge Design 8vo, 2 50- 

Merriman & Jacoby's Text- book of Roofs and Bridges. 
Part IV., Continuous, Draw, Cantilever, Suspension, and 

Arched Bridges 8vo, 2 50' 

*Morison's The Memphis Bridge Oblong 4to, 10 00 

Waddell's De Poutibus (a Pocket-book for Bridge Engineers). 

16mo, morocco, 3 00' 

" Specifications for Steel Bridges 12mo, 1 25 

Wood's Construction of Bridges and Roofs 8vo, 2 00 

Wright's Designing of Draw Spans. Parts I. and II..8vo, each 2 50 

•' " " Complete 8vo, 3 50 

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Bolton's Student's Guide in Quantitative Analysis 8vo, 1 50 

Classen's Analysis by Electrolysis. (HerrickandBoltwood.).8vo, 3 00' 

4 



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Bavenport's Statistical Methods witli Special Reference to Bio- 
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Erdmann's Introduction to Chemical Preparations. (Dunlap.) 

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" Qualitative " " (Johnson.) 8vo, 

(Wells.) Trans. 

16th German Edition 8vo, 

Puertes's Water and Public Health 12nio, 

" Water Filtration Works 12mo, 

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Hopkins' Oil-Chemist's Hand-book 8vo, 

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" Handbook for Chemists of Beet Sugar Houses. 

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Stockbridge's Rocks and Soils Svo, 

* Tillman's Descriptive General Chemistry Svo, 

5 



i3 


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50 


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00. 



Van Deventer's Physical Chemistry for Beginners. (Boltwood.) 

13mo, 

Wells's Inorganic Qualitative Analysis 12mo, 

" Laboratory Guide in Qualitative Chemical Analysis. 

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Whipple's Microscopy of Drinking-water 8vo, 

Wiechmann's Chemical Lecture Notes 12mo, 

" Sugar Analysis Small 8vo, 

WuUing's Inorganic Phar. and Med. Chemistry ISnio, 

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Hill's Shades and Shadows and Perspective 8vo, 

MacCord's Descriptive Geometry 8vo, 

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Mahan's Industrial Drawing. (Thompson.) 2 vols., 8vo, 

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" Mechanical Drawing and Elementary Machine Design. 

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Wilson's Free-hand Perspective 8vo, 

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Barker's Deep-sea Soundings 8vo, 2 00 

Benjamin's Voltaic Cell 8vo, 3 00 

History of Electricity 8vo, 3 00' 



2 00 


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4 OO 


3 50- 


5 00 


2 00 


3 00 


2 50 


3 50 


1 25 


1 00 


1 00 


7 50 


1 25 


15- 


2 50 


1 50 


3 00 


2 50 


2 00 


2 50 



5 00 


25 00 


7 50 


2 50 


2 00 


75 


3 00 



Classen's Analysis by Electrolysis. (Henick and BoltwootL) 8vo, $3 00 
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Dawson's Electric Railways and Tramways. Small, 4to, half 

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* "Engineering" and Electric Traction Pocket-book. 16mo, 

morocco, 

* Dredge's Electric Illuminations. . . .2 vols., 4to, half morocco, 

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Gilbert's De magnete. (Mottelay.) 8vo, 

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(Lorenz.) ,...12mo, 1 00 

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Thurston's Stationary Steam Engines for Electric Lighting Pur- 
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ENGINEERING. 

Civil — Mechanical — Sanitary, Etc. 

See also Bridges, p. 4 ; Hydraulics, p. 9 ; Materials of En- 
gineering, p. 11 ; Mechanics and Machinery, p. 12 ; Steam 
Engines and Boilers, p. 14.) 

Baker's Masonry Construction ,,,..,.... .8vo, 5 00 

" Surveying Instruments , 12mo, 3 00 

Black's U. S. Public Works Oblong 4to, 5 00 

Brooks's Street-railway Location 16mo, morocco, 1 50 

Butts's Civil Engineers' Field Book .IGmo, morocco, 2 50 

Byrne's Highway Construction 8vo, 5 00 

" Inspection of Materials and Workmanship 16mo, 3 00 

Carpenter's Experimental Engineering 8vo, 6 00 

Church's Mechanics of Engineering — Solids and Fluids 8vo, 6 00 

7 



6 00 


4 00 


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2 50 


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1 50 


2 00 



Church's Kotes and Examples in Mechanics 8vo, $3 00 

Crandall's Earthwork Tables ' 8vo, 1 50 

' ' The Transition Curve 16mo, morocco, 1 50 

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Eissler's Explosives — Nitroglycerine and Dynamite Svo, 

Frizell's Water Power Svo, 

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Fowler's Coffer-dam Process for Piers Svo. 

Fuertes's Water Filtration Works 12mo, 

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Godwin's Railroad Engineer's Field-book 16mo, morocco, 

Goodrich's Economic Disposal of Towns' Refuse Demy Svo, 

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Hazlehurst's Towers and Tanks for Cities and Towns Svo, 

Howard's Transition Curve Field-book 16mo, morocco, 

Howe's Retaining Walls (New Edition.) 12mo, 

Hudson's Excavation Tables. Vol. II Svo, 

Button's Mechanical Engineering of Power Plants Svo, 

" Heat and Heat Engines Svo, 

Johnson's Materials of Construction Svo, 

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Kiersted's Sewage Disposal 12mo, 

Mahau's Civil Engineering. (Wood. ) Svo, 

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" Sanitary Engineering Svo, 

Nagle's Manual for Railroad Engineers 16mo, morocco, 

Ogden's Sewer Design 12mo, 

Patton's Civil Engineering ,8vo, half morocco, 

" Foundations Svo, 

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Pratt and Alden's Street-railway Road-beds Svo, 

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Schuyler's Reservoirs for Irrigation Large Svo, 

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" Railroad Spiral 16mo, morocco, 

Siebert and Biggin's Modern Stone Cutting and Masonry, . .Svo, 

Smart's Engineering Laboratory Practice 12mo, 

Smith's Wire Manufacture and Uses Small 4to, 

Spalding's Roads and Pavements 12mo, 

8 



5 00 


3 00 


4 00 


2 


50 


2 


50 


1 


00 


2 


50 


3 50 


2 


50 


2 


50 


1 


50 


1 


25 


1 


00 


5 


00 


5 00 


6 00 


4 00 


5 


00 


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25 


5 00 


2 


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3 


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25 


5 00 


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50 


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2 00 



Spalding's Hydraulic Cement 12mo, 

Taylor's Prismoidal Formulas and Earthwork 8vo, 

Thurston's Materials of Construction 8vo, 

Tillson's Street Pavements and Paving Materials 8vo, 

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* ' ' Cross-section Sheet, 

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* " Laying Out Curves 12mo, morocco, 

Turneaure and Russell s Public "Water-supplies Svo, 

Waddell's De Pontibus (A Pocket-book for Bridge Engineers). 

16mo, morocco, 

Wait's Engineering and Architectural Jurisprudence Svo, 

Sheep, 

" Law of Field Operati in Engineering, etc Svo, 

Sheep, 

"Warren's Stereotomy — Stoue-cutting Svo, 

"Webb's Engineering Instruments. New Edition. 16mo, morocco, 

" Railroad Construction Svo, 

Wegmanu's Construction of Masonry Dams 4to, 

"Wellington's Location of Railways Small Svo, 

Wheeler's Civil Engineering Svo, 

Wilson's Topographical Surveying Svo, 

Wolff's Windmill as a Prime Mover Svo, 

HYDRAULICS. 

(See also Engineeking, p. 7.) 
Bazin's Experiments upon the Contraction of the Liquid Vein. 

(Trautwine. ) Svo, 2 00 

Bovey's Treatise on Hydraulics Svo, 4 00 

Church's Mechanics of Engineering, Solids, and Fluids. . . .Svo, 6 00 

Coffin's Graphical Solution of Hydraulic Problems 12mo, 2 50 

Ferrel's Treatise on the Winds, Cyclones, and Tornadoes. . .Svo, 4 00 

Fol well's Water Supply Engineering Svo, 4 00 

Frizeil's Water-power 8vo, 5 00 

Fuertes's Water and Public Health 12mo, 1 50 

Water Filtration Works 12mo, 2 50 

Ganguillet & Kutter's Flow of Water. (Hering & Trautwine.) 

Svo, 4 00 

Hazen's Filtration of Public Water Supply Svo, 3 00 

Hazlehursfs Towers and Tanks for Cities and Towns Svo, 2 50 

Herschel's 115 Experiments Svo, 2 00 

Kiersted s Sewage Disposal 12mo, 1 25 

Mason's Water Supply 8vo, 5 00 

" Examination of Water 12mo, 1 25 

Merriman's Treatise on Hydraulics. . . . , Svo, 4 00 



2 00 


1 50 


5 00 


4 00 


5 00 


25 


2 00 


2 50 


5 00 


3 00 


6 00 


6 50 


5 00 


5 50 


2 50 


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4 00 


5 00 


5 00 


4 00 


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3 00 



$2 50« 


5 oa 


5 00 


10 00 


5 00 


3 5a 


4 OO 


2 OO 


3 00 



Nichols's Water Supply (Chemical and Sanitary) 8vo, 

Schuyler's Reservoirs for Irrigation Large 8vo, 

Turueaure and Russell's Public Water-supplies 8vo, 

Wegmaun's Water Supply of the City of New York 4to, 

Weisbach's Hydraulics. (Du Bois.) 8vo, 

Whipple's Microscopy of Drinking Water 8vo, 

Wilson's Irrigation Engineering 8vo, 

" Hydraulic and Placer Mining : 12mo, 

Wolff's Windmill as a Prime Mover 8vo, 

Wood's Theory of Turbines 8vo, 2 50 

LAW. 

Davis's Elements of Law 8vo, 

' ' Treatise on Military Law 8vo, 

Sheep. 

Manual for Courts-martial 16mo, morocco, 

Wait's Engineering and Architectural Jurisprudence 8vo, 

Sheep, 

" Law of Contracts Svo, 

" Law of Operations Preliminary to Construction in En- 
gineering and Architecture Svo, 

Sheep, 
Winthrop's Abridgment of Military Law 12mo, 

MANUFACTURES. 

Allen's Tables for Iron Analysis 8vo, 

Beaumont's Woollen and Worsted Manufacture 12mo, 

Bolland's Encyclopaedia of Founding Terms 12mo, 

" The Iron Founder 12mo, 

" " " " Supplement 12mo, 

Eissler's Explosives, Nitroglycerine and Djmamite Svo, 

Ford s Boiler Making for Boiler Makers ISmo, 

Metcalfe's Cost of Manufactures Svo, 

Metcalf 's Steel — A Manual for Steel Users 12mo, 

* Reisig's Guide to Piece Dyeing Svo, 

Spencer's Sugar Manufacturer's Handbook . . . .16mo, morocco, 
" Handbook for Chemists of Beet Sugar Houses. 

16mo, morocco, 

Thurston's Manual of Steam Boilers 8vo, 

Walke's Lectures on Explosives Svo, 

W est's American Foundry Practice 12mo, 

' ' Moulder's Text-book 12mo, 

Wiechmann's Sugar Analysis. . . Small Svo, 

Woodbury's Fire Protection of Mills Svo, 

10 



2 50> 


7 00 
7 50 


1 50 


6 00- 
6 50^ 


3 OQr 


5 00 
5 50 


2 50'' 



3 00 


1 50 


3 00' 


2 50 


2 50' 


4 OO 


1 00' 


5 OO 


2 OO 


25 OO 


2 00 


3 00- 


5 00 


4 00 


2 50 


2 50 


2 50 


3 50^ 



MATERIALS OF ENGINEERING. 

{See also Engineering, p. 7:) 

Baker's Masonry Construction 8vo, 

Bovey's Strength of Materials 8vo, 

Burr's Elasticity and Resistance of Materials 8vo, 

Byrne's Highway Construction 8vo, 

Church's Mechanics of Engineering — Solids and Fluids 8vo, 

Du Bois's Stresses in Framed Structures Small 4to, 

Johnson's Materials of Construction 8vo, 

Lanza's Applied Mechanics 8vo, 

Martens's Testing Materials. (Henuing. ) 3 vois., 8vo, 

Merrill's Stones for Building and Decoration .8vo, 

Merriman's Mechanics of Materials 8vo, 

" Strength of Materials 12mo, 

Patten's Treatise on Foundations 8vo, 

Rockwell's Roads and Pavements in Prance 12mo, 

Spalding's Roads and Pavements 12mo, 

Thurston's Materials of Construction ,. 8vo, 

" Materials of Engineering 3 vols., Svo, 

Vol. I., Non-metallic 8vo, 

Vol. II. , Iron and Steel 8vo, 

Vol. III., Alloys. Brasses, and Bronzes 8vo, 

Wood's Resistance of Materials Svo, 

MATHEMATICS. 

Baker's Elliptic Functions Svo, 

*Bass's Differential Calculus 12mo, 

Briggs's Plane Analytical Geometrj' 12mo, 

Chapman's Theory of Equations .12mo, 

Comptou's Logarithmic Computations 12mo, 

Davis's Introduction to the Logic of Algebra Svo, 

Halsted's Elements of Geometry c.Svo, 

" Synthetic Geometry Svo, 

Johnson's Curve Tracing 12mo, 

" Differential Equations — Ordinary and Partial. 

Small Svo, 

" Integral Calculus 12mo, 

" " " Unabridged. Small 8vo. {In press.) 

" Least Squares 12mo, 

*Ludlow's Logarithmic and Other Tables. (Bass,) Svo, 

* " Trigonometry with Tables. (Bass.) Svo, 

*Mahan's Descriptive Geometry (Stone Cutting) Svo, 

Merriman and Woodward's Higher Mathematics Svo, 

11 



$5 OO 


7 50 


5 00 


5 00 


6 00 


10 00 


6 00 


7 50 


7 50 


5 00 


4 00 


1 00 


5 00 


1 25 


2 00 


5 00 


8 00 


2 GO 


3 50- 


2 50- 


3 00- 


1 50 


4 00 


1 00 


1 50 


1 50 


1 50 


1 75 


1 50 


1 00 


3 50 


1 50 


1 50' 


2 00' 


3 00 


1 50 


5 00. 



Merriman's Method of Least Squares 8vo, 

Rice and Johnson's Differential and Integral Calculus, 

2 vols, in 1, small 8vo 

" Differential Calculus. Small 8vo 

" Abridgment of Differential Calculus. 

Small 8vo 

Totten's Metrology 8vo 

"Warren's Descriptive Geometry 2 vols., 8vo 

" Drafting Instruments 12m0; 

" Free-hand Drawing 12mo 

" Linear Perspective 12mo 

" Primary Geometry 12mo 

" Plane Problems, 12mo 

" Problems and Theorems 8vo 

" Projection Drawing 12mo 

"Wood's Co-ordinate Geometry 8vo 

" Trigonometry 12mo 

"Woolf's Descriptive Geometry Large 8vo 



S2 00 



, 2 


50 


, 3 


00 


, 1 


•50 


, 2 


50 


), 3 


50 


), 1 


25 


), 1 


00 


), 1 


00 


), 


75 


), 1 


25 


), 2 


50 


\ 1 


50 


), 2 


00 


), 1 


00 


), 3 00 



MECHANICS-MACHINERY. 

{See also Engineering, p. 7.) 

Baldwin's Steam Heating for Buildings 12mo, 

Barr's Kinematics of Machinery 8vo, 

Benjamin's Wrinkles and Recipes 12mo, 

Chordal's Letters to Mechanics 12mo, 

Church's Mechanics of Engineering 8vo, 

" Notes and Examples in Mechanics 8vo, 

Crehore's Mechanics of the Girder 8vo, 

Cromwell's Belts and Pulleys 12mo, 

" Toothed Gearing 12mo, 

Compton's First Lessons in Metal Working 12mo, 

Compton and De Groodt's Speed Lathe 12mo, 

Dana's Elementary Mechanics 12mo, 

Dingey's Machinery Pattern Making 12mo, 

* Dredge's Trans. Exhibits Building, World Exposition. 

Large 4to, half morocco, 

Du Bois's Mechanics. Vol. I., Kinematics „ Svo, 

Vol. IL, Statics 8vo, 

" Vol. IIL, Kinetics Svo, 

Fitzgerald's Boston Machinist ISmo, 

Flather's Dynamometers 12mo, 

" Rope Driving 12mo, 

Hall's Car Lubrication 12mo, 

HoMy's Saw Filing 18mo, 

12 



50 
50 
00 
00 
00 
00 
00 
50 
50 
1 50 



2 00 

5 00 

3 50 

4 00 
3 50 

1 00 

2 00 
2 00 
1 00 

75 



* Johuson's Theoretical Mechanics. An Elementary Treatise. 

12uio, |3 00 

Jones's Machine Design. Part I., Kinematics 8vo, 1 50 

" " " Part II., Strength and Proportion of 

Mtichiue Parts 8vo, 3 00 

Lanza's Applied Mechanics 8vo, 7 50 

MacCord's Kinematics 8vo, 5 00 

Merriman's Mechanics of Materials 8vo, 4 00 

Metcalfe's Cost of Manufactures 8vo, 5 GO 

*Michie's Analytical Mechanics 8vo, 4 00 

Richards's Compressed Air 12mo, 1 .50 

Robinson's Principles of Mechanism 8vo, 3 00 

Smith's Press-working of Metals .8vo, 8 00 

Thurston's Friction and Lost Work 8vo, 3 00 

' ' The Animal as a Machine 12mo, 1 00 

Warren's Machine Construction 2 vols., 8 vo, 7 50 

Weisbach's Hydraulics and Hydraulic Motors. (Du Bois.)..8vo, 5 00 
'■ Mechanics of Engineering. Vol. III., Part I., 

Sec. I. (Klein.) 8vo, 5 00 

Weisbach's Mechanics of Engineering. Vol. III., Part I., 

Sec. II. (Klein.) 8vo, 5 00 

Weisbach's Steam Engines. (Du Bois.) 8vo, 5 00 

Wood's Analytical Mechanics 8vo, 3 00 

" Elementary Mechanics 12mo, 1 25 

" " " Supplement and Key 12mo, 1 25 



METALLURGY. 

Allen's Tables for Iron Analysis 8vo 

Egleston's Gold and Mercury Large 8vo 

" Metallurgy of Silver Large 8vo 

* Kerl's Metallurgy— Steel, Fuel, etc 8vo 

Kunhardt's Ore Dressing in Europe , 8vo 

Metcalf's Steel — A Manual for Steel Users , 12mo 

O'Driscoll's Treatment of Gold Ores 8vo 

Thurston's Iron and Steel 8vo 

" Alloys 8vo 

Wilson's Cyanide Processes 12mo 

MINERALOGY AND MINING. 



8 00 

7 50 

7 50 

15 OO 

1 50 

2 00 

2 00 

3 50 
2 50 
1 50 



Barringer's Minerals of Commercial Value. . ..Oblong morocco, 2 50 

Beard's Ventilation of Mines 12mo, 2 50 

Boyd's Resources of South Western Virginia 8vo, 3 00 

" Map of South Western Virginia Pocket-book form, 2 00 

Brush and Penfield's Determinative Mineralogy. New Ed. 8vo, 4 00 

13 



-Chester's Catalogue of Minerals 8vo, 

" " " " Paper, 

" Dictionary of the Names of Minerals 8vo, 

-Dana's American Localities of Minerals Large 8vo, 

" Descriptive Mineralog}'. (E. S.) Large 8vo. half morocco, 

" First Appendix to System of Mineralogy Large 8vo, 

" Mineralogy and Petrography. (J. D.) 12mo, 

" Minerals and How to Study Them. (E. S.) 13mo, 

" Text-book of Mineralogy. (E. S.).. .New Edition. Svo, 

* Drinker's Tunnelling, Explosives, Compounds, and Rock Drills. 

4to, half morocco, 

Egleston's Catalogue of Minerals and Synonyms Svo, 

Eissler's Explosives — Nitroglycerine and Dynamite 8vo, 

Hussak's Pock-forming Minerals. (Smith.) Small Svo, 

Ihlseng's Manual of Mining Svo, 

Kunhardt's Ore Dressing in Europe , Svo, 

O'Driscoll's Treatment of Gold Ores Svo, 

* Penfield's Record of Mineral Tests Paper, Svo, 

Eosenbusch's Microscopical Physiography of Minerals and 

Rocks. (Iddings.) Svo, 

Sawyer's Accidents in Mines Large Svo, 

iStockbridge's Rocks and Soils Svo, 

*Tillman's Important Minerals and Rocks Svo, 

Walke's Lectures on Explosives .Svo, 

Williams's Lithology Svo, 

Wilson's Mine Ventilation 12mo, 

" Hydraulic and Placer Mining 12mo, 2 50 

STEAM AND ELECTRICAL ENGINES, BOILERS, Etc. 

{See also Engineering, p. 7.) 

^Baldwin's Steam Heating for Buildings 12mo» 2 50 

Clerk's Gas Engine Small Svo, 4 00 

Tord's Boiler Making for Boiler Makers 18mo, 1 00 

Hemenway's Indicator Practice 12mo, 2 00 

.Kent's Steam-boiler Economy Svo, 4 00 

Kneass's Practice and Theory of the Injector Svo, 1 50 

MacCord's Slide Valve 8vo, 2 00 

IVEeyer's Modern Locomotive Construction 4to, 10 00 

Peabody and Miller's Steam-boilers Svo, 4 00 

Peabody's Tables of Saturated Steam Svo, 1 00 

" Thermodynamics of the Steam Engine Svo, 5 00 

" Valve Gears for the SteamEngine Svo, 2 50 

" Manual of the Steam-engine Indicator 12mo, 1 50 

Pray's Twenty Years with the Indicator Large Svo, 2 50 

14 



50 


3 00 


1 00 


12 50 


1 00 


2 00 


1 50 


4 00 


25 00 


2 50 


4 00 


2 00 


4 00 


1 50 


2 00 


50 


5 00 


7 00 


2 50 


2 00 


4 00 


3 00 


1 25 



6 00 


10 00 


75 


1 50 


2 50 


5 00 


2 50 


1 00 


5 00 


5 00 


2 50 


4 00 



Piipin and Osterberg's Thermodynamics 12mo, $1 25 

Reagan's Steam and Electric Locomotives 12mo, 2 00 

Routgen's Tliermodyuamics. (Du Bois. ) 8vo, 5 00 

^"Sinclair's Locomotive Running .12mo, 2 00 

/"Snow's Steam-boiler Practice 8vo. 3 00 

'Thurston's Boiler Explosions 12mo, 1 50 

" Engine and Boiler Trials 8vo, 5 00 

" Manual of the Steam Engine. Part I., Structure 

and Theory Svo, 6 00 

" Manual of the Steam Engine. Part II,, Design, 

Construction, and Operation Svo, 

2 parts, 

" Philosophy of the Steam Engine 12mo, 

" Reflection on the Motive Power of Heat. (Caruot.) 

12mo, 

" Stationary Steam Engines Svo, 

" Steam-boiler Construction and Operation Svo, 

Spangler's Valve Gears , Svo, 

' ' Notes on Thermodynamics 12mo, 

Weisbach's Steam Engine. (Du Bois.) Svo, 

Whitham's Steam-engine Design, .^.o Svo, 

Wilson's Steam Boilers. (Flather.) , , 12mo, 

Wood's Thermodynamics, Heat Motors, etc Svo, 

TABLES, WEIGHTS, AND MEASURES. 

, Adriance's Laboratory Calculations 12mo, 1 25 

Allen's Tables for Iron Analysis Svo, 3 00 

Bixby's Graphical Computing Tables Sheet, 25 

Compton's Logarithms 12mo, 1 50 

Crandall's Railway and Earthwork Tables Svo, 1 50 

Davis's Elevation and Stadia Tables , Small Svo, 1 00 

Fisher's Table of Cubic Yards Cardboard, 25 

Hudson's Excavation Tables. Vol. II Svo, 1 00 

Johnson's Stadia and Earthwork Tables , Svo, 1 25 

Ludlow's Logarithmic and Other Tables. (Bass.) .12mo, 2 00 

Totten's Metrology Svo, 2 50 

VENTILATION. 

Baldwin's Steam Heating 12mo, 2 50 

Beard's Ventilation of Mines 12mo, 2 50 

Carpenter's Heating and Ventilating of Buildings Svo, 3 00 

Oerhard's Sanitar}^ House Inspection 12mo, 1 00 

IVilson's Mine Ventilation 12rao, 1 25 

15 



MISCELLANEOUS PUBLICATIONS. 

Alcott's Gems, Sentiment, Language .Gilt edges, $5 OOi 

Emmou's Geological Guide-book of the Rocky Mountains. .8vo, 1 50 

Ferrel's Treatise on the Winds 8vo, 4 00 

Haines's Addresses Delivered before the Am. Ry. Assn. ..13mo, 2 50 

Mott's The Fallacy of the Present Theory of Sound. .Sq. 16mo, 1 OO 

Richards's Cost of Living 12mo, 1 00 

Ricketts's History of Eensselaer Polytechnic Institute 8vo, 3 00 

Rotherham's The New Testament Criticallj-- Emphasized. 

12mo, 1 50 
" The Emphasized New Test. A new translation. 

Large 8vo, 3 00 

Totten's An Important Question in Metrology 8vo, 3 50 

HEBREW AND CHALDEE TEXT=BOOKS. 

For Schools and Theological Seminaries. 

Gesenius's Hebrew and Chaldee Lexicon to Old Testament. 

(Tregelles.) Small 4to, half morocco, 5 00 

Green's Elementary Hebrew Grammar 12mo, 1 25 

" Grammar of the Hebrew Language (New Edition). 8vo, 3 00 ■ 

" Hebrew Chrestomathy 8vo, 3 00 

Lettevis's Hebrew Bible (Massoretic Notes in English). 

8vo, arabesque, 2 25 

MEDICAL. 

Hammarsteu's Physiological Chemistry. (Maudel.) 8vo, 4 00 

Mott's Composition, Digestibility, and Nutritive Value of Food. 

Large mounted chart, 1 25 

Ruddiman's Incompatibilities in Prescriptions 8vo, 2 00 

Steel's Treatise on the Diseases of the Dog 8vo, 3 50 

WoodhuH's Military Hygiene , 16mo, 1 50 

"Worcester's Small Hospitals — Establishment and Maintenance, 
including Atkinson's Suggestions for Hospital Archi- 
tecture 12mo, 1 35 

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